As Boring As It Gets: Managing Geotechnical Data with ... · As "Boring" As It Gets: Managing Geotechnical Data with Autodesk® Civil Technology Shawnita Sterett, P.E. CV23-3 Soil

December 2-5, 2003 ◊ MGM Grand Hotel Las Vegas

As "Boring" As It Gets: Managing Geotechnical Data with Autodesk® Civil

Technology

Shawnita Sterett, P.E.

CV23-3 Soil borings provide valuable information regarding subsurface layers. During this session, we'll take advantage of new surface modeling features in Autodesk® Civil 3D in conjunction with tools in Autodesk® Land Desktop 2004 to manage subsurface data in cross sections, profiles, and quantities.

As "Boring" As It Gets: Managing Geotechnical Data with Autodesk® Civil Technology

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Introduction Autodesk® Civil Engineering Solutions include a number of great tools to manage and utilize geotechnical data such as soil borings. By utilizing both the point management and database functionality with Autodesk® Land Desktop 2004 and the new surface modeling capabilities of Autodesk® Civil 3D 2004, a designer has quick and easy access to additional engineering information.

Types of Data During this session, we’ll be utilizing soil boring data in two forms. First, we’ll work with a database with tables containing the soil boring data in records. Second, we’ll use the actual boring logs that have been scanned into an image format from the geotechnical engineers report. Although this class will focus on the use of geotechnical soil borings, the concepts for managing point data, surfaces, and external documents have many other applications.

Creating Point Data To begin managing our geotechnical soil boring information in our Land Desktop or Civil 3D Project, we’ll first need to create point locations for that data. Often, these points will actually represent surveyed locations of soil borings in the field. The data may be imported with traditional survey import methods or may be manually created in the drawing. During this class, we’ll cover the basics of creating point data in Land Desktop and later look at sharing that data with Autodesk Civil 3D 2004.

Point Objects In both Autodesk Land Desktop (LDT) and Autodesk Civil 3D (C3D), points are represented with a special element called a point object. The exact specifications of that object vary between LDT and C3D, but their personalities are very similar. For instance, the annotation of the point can easily be moved without changing the coordinates of the point data. In addition, simply right-clicking on a point will give you a context-sensitive menu for the point data.

LDT Point Settings Depending on how you set up options in the point settings, each time you set a point, you may be prompted for descriptions, elevations, and point numbers, or these features can be created automatically.

1. Points Point Settings

2. Select the Create tab

3. Toggle on Insert to Drawing as Created

4. Toggle on Sequential Numbering

5. Set the Elevation to Manual

6. Set the Description to Manual


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With these settings, when creating points using the Points pull-down menu, you will be prompted to enter elevation and description information. When inserting points using the Points pull-down menu, point numbers will be automatically assigned. Also, you will not prompted for point numbers, as they will be automatically assigned sequentially, beginning with the current point number. When creating points using Autodesk Survey, an ASCII file, or LandXML import, these settings will be overridden by the values specified in the file.

Use the point insertion settings to control what the search path is for symbols inserted with point labels or description keys, whether to insert points at actual or fixed elevations, and whether to use the current label style when inserting or creating points.

7. Select the Insert tab

8. Set the Search Path to the location of plan symbols standard for your office

9. Set the Insertion Elevation to Fixed

10. Specify the Fixed Elev to be 0

Specifying the Insertion Elevation to the actual elevation can result in 3D distances being returned when using the AutoCAD distance command. In addition, if you created AutoCAD line command in conjunction with the node osnap, you may end up with 3D lines between your points.

11. Toggle on the option to Use Current Label Style…

Label styles allow you to create points with a custom look. We will look closer at using custom label styles and description keys which are both dependent on this setting more during this class.

12. Select the Update tab

13. Turn off the option to Allow Points to be Moved in Drawing

Turning off this setting will prevent AutoCAD move commands from accidentally moving the point location out of alignment with our project database. The MOVE command will move the point annotation only while leaving the point node in its original location.

14. Select the DescKeys tab

15. Toggle on the Ascending Search Order

16. Toggle on Match on Description Parameters

17. Toggle on Perform Extended Default Search…

We can use description keys to associate symbols with points, to place points on specific layers, and to substitute full descriptions for abbreviated field descriptions. We’ll look at how description keys may be used in conjunction with label styles.

When you create points, you can enter a description key at the Description prompt. The program searches for corresponding description key in the description key file. If the key is found, then the full description, point layer, and symbol information are retrieved from the description key file. If the key is not found, then the entered key is used as the description for the point.


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Description keys are also used when you insert existing points into the drawing from the point database file, or when you import points into the drawing from an external file or user database. When the point is inserted into the drawing, the point layer and symbol associations of the description key file are applied to the points.

In the Description Key Search Order, you can search the description key database in an ascending order, or descending order.

Select Ascending to search the description key file from top to bottom. The ascending option searches the file from A to Z. In the ASCII character sequence, A is the lowest number of the alphabet, and Z is the highest number in the alphabet, which is why a search of this type is called ascending. For example, if you select Ascending, the description key ST* is used before the description key STA*, and every description starting with ST would use the ST* description key.

Select Descending to search the description key file from bottom to top. If you select Descending, then the STA* description key would be used before ST*, so that every description starting with STA would use the STA* description key. Then, if there are other descriptions that start with ST (but not STA), they would use the ST* description key.

Select the Match on Description Parameters ($1, $2, etc.) check box to use description parameters in the description format, and for scaling and rotating the description key symbols. We will not use this setting during this class, but this may be a very useful tool when working with data like trees.

Select the Perform Extended Default Search for DescKeys in DEFAULT.MDB check box if you would like to search the DEFAULT description key file for matching description keys, after the current description key file is searched and a match is not found.

18. Select the Marker tab

19. Select Use Custom Marker

20. Select the Custom Marker Style you prefer

21. Set an optional superimposed shape on your marker (if preferred)

22. Customer Marker Size should be set to Absolute with a value that looks appropriate to your scale and preference. Usually between 1 and 5.

23. Check “Align Marker With Text Rotation”

Alternatively, you can select Use AutoCAD POINT for Marker if you want to use an AutoCAD point type as the point marker. If you select this option, then the other options in the dialog box are grayed out. To change the AutoCAD point type you can use the DDPTYPE, PDMODE, and PDSIZE commands.

Note that you can also select Size Relative to Screen if you want the point marker size to be scaled to a fixed percentage of the AutoCAD graphics screen. This option maintains the relative size of the point marker to the screen regardless of the zoom level. If you select this option, then type the percentage in the Size box. This makes it easy to see the point marker regardless of the current view on the screen. This option is less desirable for plotting.

24. Select the Text tab

25. Under Color and Visibility, set the visibility and color of each component to meet your preferences

26. Select Show Full Descriptions to show the descriptions after description key matching is applied

The description key settings of the point label style that is current at the time the point object is inserted in the drawing are used to match the description.


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27. Under Style and Size, select a text style to use for the point markers from the Text Style list

28. Toggle Size in Absolute Units

29. Set the text to the height of your preference

30. If desired, enable “Automatic Leaders”

Note that you can also select Size Relative to Screen if you want the point text size to be scaled to a fixed percentage of the AutoCAD graphics screen. This option maintains the relative size of the point text to the screen regardless of the zoom level. If you select this option, then type the percentage in the Size box. This makes it easy to see the point text regardless of the current view on the screen. This option should be turned off if you need to plot the points with a specific height.

By enabling the automatic leaders, when you move a point using an AutoCAD command with the Update setting such that AutoCAD MOVE is not allowed to update a point, the point text will move and a leader will automatically be drawn back to the point node from the annotation.

31. Select the Preferences tab

32. Toggle on Allow Command Line Input of Point Lists

33. Toggle on Allow Command Line Input of Point Group Names

34. Toggle off Always Regenerate Point Display After Zoom

35. Toggle off Check Status on Startup

The settings described above are general preferences for efficiency. You will find very useful scenarios for alternate settings. The first two will allow for command line prompts to select points and will allow the skipping of a few dialogue boxes. The regenerate after zoom option is very useful if you are working with points that have marker and text set relative to screen. Otherwise, you won’t automatically see the size adjustment.

The Point Group Manager (PGM) check status on startup is very useful if you are working on adding data to a project that already has point groups defined. Then the PGM will automatically give you indicators letting you know which groups need to be updated per your changes. If you have a large point data base with many groups, you may find that always checking at each entry to the PGM will be very time consuming.


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Managing Point Data In this example, the points have already been added to our Land Desktop project which is external to the drawing file. We will organize the point data using the Point Group Manager and Description Keys. Then, we will display the data in our current drawing utilizing point label styles.

Point Groups Point groups are a very useful way to organize our point databases into managable chunks. For example, you may like to sort tree points, traverse points, or point staking locations into separate groups for easy reference. They may be used for export, import into the drawing, labeling, and surface creation.

1. Points Point Management Point Group Manager

2. Select the Create Point Group button

3. Name the Group “All Points”

4. Select the Include Tab

5. Check Include ALL Points

Point Groups in Land Desktop 2004 are dynamic such that this group will always “remember” that it includes all points. At any time additional data is added to the project, the group may be updated to include that new data by simply selecting the Update All Point Groups button. If you would like to update only one point group, you may get to an appropriate option by simply right-clicking on the desired point group.

In this example, we can see our boring data in points #2055-2084. Notice that they all have descriptions such as “B1”, “B22”, etc. This decription format can be added to our description key file for easy creation of symbols in our drawing.

Description Keys As described earlier, we can use description keys to associate symbols with points, to place points on specific layers, and to substitute full descriptions for abbreviated field descriptions. We’ll use description keys in this case to help sort our point data and to automatically place symbols on the appropriate AutoCAD layers.

6. Points Point Management Description Key Manager

7. Highlight the “Default” description key file

8. Select the “Create DescKey” button

9. Enter B#* for the description key code

Wildcard characters such as * may be used as part of a description key code. In this example, we are using the number filter, #. The #* combination will accept any descriptions which have a number, followed by any alphanumeric sequence. The following table summarizes wildcard characters that may be used in the creation of description keys and point groups.


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Character Definition

# (pound) Matches any single numeric digit

@ (at) Matches any alphabetic character

. (period) Matches any non-alphanumeric character

* (asterisk) Matches any string and can be used anywhere in the search string

? (question mark) Matches any single character, for example, ?BC matches ABC, 3BC, and so on

~ (tilde) Matches anything but the pattern, for example, ~*AB* matches all strings that don’t contain AB

[...] Matches any one of the characters enclosed, for example, [AB]C matches AC and BC

[~...] Matches any character not enclosed, for example, [~AB]C matches XC but not AC

- (hyphen) Inside brackets, specifies a range for a single character, for example [A-G]C matches AC, BC, and so on to GC, but not HC

(reverse quote) Reads the next character literally, for example, *AB matches *AB

10. Enter $* for the description format

11. Enter appropriate layer, symbol, and symbol layer

Multiple strings from the raw description may be included in a description format. They are differentiated by the order they were entered, ie. $0, $1, $2, etc. In this case, we are simply using a generic description that will look identical to the raw description entered for the point no matter how many strings or parameters were included.

Point Groups from Description Keys 12. Points Point Management Point Group Manager

13. Select the Create Point Group button

14. Name the new group “Borings”

15. Select the Raw Desc Matching tab

16. Check B#*

17. Select OK

Inserting Points from a Point Group 18. In the Point Group Manager, right-click on the Borings

Point Group

19. Select Insert Points to Drawing

20. Alternatively, Use Points Insert Points to Drawing


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Managing Geotechnical Data As with most projects that contain geotechnical data, our data was delivered in the form of a paper report. In this scenario, the report was scanned, and the strata information was entered into a database.

Once the point data is entered in the database, it can be linked to the point data in the LDT project to give you more than just the standard point number, elevation, and description for the point.

The database was created in Microsoft Access format, and the key column in the database matched the point numbers of the survey points representing the location of the borings. This will allow us to externally reference (XDRef) the survey points with the additional strata data in the database. We will be able to extract this data for creating terrain models of the different strata, as well as labeling it in plan using a custom label style.

Creating the User Database In Land Desktop, the Access databases used to create external references or XDRefs for point data are called “user” databases. They have a specific format and are stored as an Access 97 file. Many casual users of Access find it cumberson and difficult to navigate. In order to simplify the creation and management of this data, a utility is included in Land Desktop to create, edit, and manage the user defined data base.

1. At the command line, type “userdbmanager”

2. Use the Create User DB button to create a new database. The database should be stored at your project storage location under projectname\cogo\userdb\filename.mdb

3. Use the Create Table button to create a table in your new database. Do not include any spaces in the table name.

4. Expand the tree under your new database to see the new table name.

5. Highlight the new table name. Note that the buttons at the top of the manager change.

6. Select the Create Column button to add columns to your table.

Notice that a PNO column is already added to the table. This column will be used to match up point numbers in the external database to points in the Land Desktop project. It is a necessary column for any situation where you would like to use XDRefs.

Commands within this utlity will also allow you to create entries into tables. Depending on your comfort with Access, you may find this a very useful alternative to entering data with Access. If you chose to open the file in a version of Access more current than Access 97, you will get a prompt when you open the file. Chose to open without conversion, and you will have no problem adding records to your database and utilizing XDRefs in Land Desktop. If you need to add or delete columns, use the UserDBManager utility inside of Land Desktop.


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Creating the XDRefs AutoCAD Land Desktop creates and maintains a point database file that contains all the point information in the project. The COGO point database stores point number, name (optional), northing, easting, elevation, and description. Utilizing XDRefs, you can also create your own customized point databases and use them to do the following:

• Substitute point data, like elevation or description, when points are accessed through a point group • Label points with data that is substituted from the custom database or label points with data that

supplements COGO point database information

7. Points Point Management XDRef Manager

8. Select the Create XDRef button

9. Name the XDref, i.e. Boring-TopSoilElev

10. Point to the appropriate database location, i.e. projectname\COGO\UserDB\borings.mdb

11. Select the Table Name from the drop-down list, i.e. Borings

12. Select the Column Name from the drop-down list, i.e. TopSoilElev

13. Select OK

14. Add additional XDRefs as desired

15. Manager Exit

The XDRefs for the boring data are now complete. In this example, we have the description, date the boring was completed, elevation information for the various strata layers, and notes about the boring itself. All of the data is relative to boring strata elevations. In a later example, we’ll look at how to effectively utilize data that is actually strata or boring depths.


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Working With Point Label Styles There are two different modes you can use to annotate point information on screen: point markers with text and point labels.

You can use point markers with or without text as a “working mode”, and then you can label the points to place additional data on the point node. You can use these point labels to simply supplement the point objects, or to replace those standard labels with a more descriptive version.

Much like labeling a line, point labels may be used when a more descriptive annotation is necessary. For example, in one scenario, you may like to label a line with a simple length. In another, you may want to use a length and a bearing. The lines are not that much different geometrically, but we use different line label styles to annotate them differently.

The following table summarizes some of the benefits of working with both Point Markers and Point Labels.

Benefits of Point Markers Benefits of Point Labels

You can set their size relative to the screen, so when you zoom in or out, they stay the same size.

You can label points with XDRef information.

You can drag the marker text away from the point node, creating a leader with an arrow.

You can label points with any amount of data: you are not limited to point number, elevation, or description. If desired, you can keep the marker text visible, showing point number, elevation, and description, and use the point labels to label the points with different information.

When using LDT commands that call for a point, you can use the running osnap for node and may snap to the point by simply mousing over the text.

You can use formulas and complex formats in labels.

Both labels and markers can exist at the same time, making a point appear like it has duplicate information. You can turn markers or labels off so that only one of the two is displayed if desired.

Creating Custom Point Label Styles 1. Labels Show Dialog Bar

The Style Properties dialog bar acts as the dashboard for the labeling tools. All of the information regarding the current style is concisely organized and easily accessed.

2. Navigate to the Point tab

3. Select pencil icon. This will enable you to edit an existing style, or create a new one.

4. Enter Boring Labels for the style name.

5. Toggle on Turn off marker text

6. In the text field, eliminate all items except the description.

7. Toggle on the option to Insert Common Symbol.

8. Select the appropriate symbol.

9. Select a layer for the symbol to appear on.

10. Set the Style to the desired text font.


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11. Set the Layer for the text.

12. Select OK to exit and save the style.

13. Set the Boring Labels style current on the dialogue bar

14. Points Insert Points to Drawing…

15. Use the option for Group

16. Use the option for Dialog

17. Select the newly created Borings group

This style will insert the boring symbol on each point in the point group we created earlier and supplement the symbol with a description label.

Supplementing Label Styles with XDRefs In the point label style, we can extract information from the data stored in the point database, as well as data stored as External Data References. 18. Labels Show Dialog Bar (unless you still have it open)

19. Navigate to the Point tab

20. Select pencil icon.

21. Enter Boring Labels - Elevations for the style name.

22. In the Text field, enter a prefix for the point number, such as “Point No: “

23. Select Point Number from the Data list.

24. Select >> Text. This will add the {Point Number} code to the description.

When label data is placed, values in brackets are replaced with the appropriate values for the specific point.

25. In the Text field, move to the next line, and enter the text “Top Soil El: “

26. Select Borings – TopSoilElev from the XDRef drop-down list.

27. Select >> Text. This will add the description field from the XDRef'd database to the point description.

28. Repeat steps 22-24 or 25-27 as necessary to include all desired components in the point label.

29. Save and exit the dialog.

Next, we will use our label in the drawing.

30. With the Label Style Properties dialog bar on the screen, select the newly created label style as current.

31. Select a Boring point, highlighting it.

32. Right-click, select Add Dynamic Label

The completed label depicts a complete set of data pertaining to the boring. Data from both the point database and external databases, as well as inherent properties of points, such as latitude and longitude can be included in a single label.


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Using Autodesk Map to Link Boring Logs with Symbols Autodesk Map functionality allows you to connect to external databases and link objects in a drawing to those databases and other external documents. In this example, we will utilize a database that has a list of the boring designations (B3, B22, etc…), and the boring documents associated with each of the records. We will use tools that allow us to generate the link between the database and drawing automatically and use that link to view the actual boring logs.

Attaching a Database We have already completed the database entry and are ready to attach the database to the drawing session. The easiest way to do this is to simply drag the database from Windows Explorer onto the Project Workspace.

1. Open Microsoft Windows Explorer

2. Locate the database containing the boring data

3. Drag the database onto the project workspace

Defining Link Templates Although we can now manipulate and analyze he data using the Data View, we have still not linked the database to the drawing. This is done via defining a Link Template.

4. Highlight the Link Templates tree on the Project Workspace.

5. Click the right mouse button

6. Select Define Link Template

7. In the Define Link Template dialog, enter a name for the link path, and select a single key.

8. Select OK

The key field should exactly match the description of the boring logs as generated with the boring label style we defined earlier. This will aid us in generating the links automatically.

Generating the Links Automatically Generating the links is about as automatic as it can get. Since the boring descriptions exactly match the key field we defined in our database (by design), we can use an automated tool to generate the links. It is a simple but important step.

9. Highlight the new Link Template in the Project Workspace

10. Right-click and select Generate Links…


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11. We will be using Text as the linkage type

12. Set the Link Template to borings (or the name that you selected)

13. Select OK

14. Use the option to select all

Defining a Document View With Autodesk Map and Autodesk Land Desktop, you can click on an object and view an associated document. In this case, we have done the pre-work of establishing the database and connection to the objects. Now we just need to define what program we will be using to view the associated documents.

15. Map Object Data Define Document View…

16. Enter a name and description for the document view definition

17. For the expression, select the Expression button

18. Within the Document View Expression dialog, select the link template attribute that contains the document name

19. For the directory, browse to the folder containing the documents to be viewed

20. In the Ext field, enter the extension of the filename type to be viewed

21. For the command line, enter the path and filename to the executable program that will be used to view the documents

22. Leave Launch Method to default

23. Select Add to add the document view definition, and save it

Viewing Documents We can now select any boring label text and view the associated geo-technical report.

24. Map Object Data View Associated Document

Select any boring label text


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Using Geotechnical Data to Build Terrain Models As we saw in previous steps, it is very easy to integrate geotechnical data into point labels. The strata information can also be represented in Point Groups which were touched on at the beginning of the session.

Creating Point Groups with XDRef Overrides When you create a point group, by default the points in that group retrieve all of their information from the COGO point database. For example, in the COGO point database, point 1 has a description of Benchmark and an elevation of 100. If you create a group that includes point 1, then the point will retrieve its data from the COGO point database and have the description Benchmark and the elevation 100.

However, you can also set up overrides for the points in a point group. Overrides can substitute Point Label Style, description, and elevation. For example, you could set up an override for the group that replaces point 1’s description, Benchmark, with a description of TOPO. The data in the point database remains unchanged, but when the point is referenced in that group, the point will have an override, TOPO, as its description.

There are two ways to override point data in point groups:

• You can override the point label style, description, or elevation with a single fixed value that is used for all points in the group.

• You can specify an XDRef name to substitute data that is in a Microsoft Access database on a point-by-point basis. Use this option if you want to override each point with a different value.

1. Points Point Management Point Group Manager

2. Highlight the Borings point group.

3. Right-click and select Copy Point Group

Because the Borings point group was selected, the properties of the group already contain the correct point filters.

4. Enter a name for the point group. (Borings – Ledge)

5. Select the Overrides tab

6. Toggle on the option to override Description

7. Enter a description of Ledge Strata. This description will be used for all points in this group, so make it generic.

8. Toggle on the option to override Elevation

9. Select the pencil icon in the Override column. This will toggle the pencil icon to a database icon.

10. Select the Override field for Elevation.

11. In the pop-up dialog, select the XDRef containing the elevation information from the database set up earlier.

12. Select OK

Now, when points are imported using the Borings – Ledge point group, they will be displayed with the ledge elevations, and descriptions set up here.


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Using Point Groups in Terrain Models With the data in the format of point groups, now it is very simple to create a Terrain Model using the ledge strata information from the geotechnical reports. This will allow us to calculate cut/fill volumes from our proposed design terrain model to the ledge terrain model, and determine the quantity of ledge cut. Because point group data can be directly referenced in Terrain Model Explorer, building the model should be a snap.

13. Terrain Terrain Model Explorer

14. Manager Create New Surface

15. Rename the Surface1 to be something more meaningful, such as Ledge Strata

16. Expand the Ledge Strata tree

17. Right-click and select “Add Point Group”

18. Select the Borings – Ledge point group

19. Select the Ledge Strata surface on the tree

20. Right-click and select Build…

Reviewing the Surface Models 21. Terrain Sections Multiple Sections On/Off

22. Make sure the command line toggle says that multiple sections are now on. If the toggle is off, repeat Step #21

23. Terrain Section Define Multiple Surfaces

24. Select both the Existing Ground and the Ledge Strata surface by holding down the Control key

25. Draw a line across the project area

26. Highlight the line

27. Right-click and select “View Quick Section”

28. Grip edit the line to drag around the project and update the quick section

You may have noticed that depending on the number of borings you have on your project site, a surface created just from the boring points may tend to cross the existing ground surface at some locations. If we make the assumption that the subsurface strata tend to mimic the natural terrain, we can extrapolate the boring depth data to reflect the existing ground surface across our project site. Let’s explore the differences of working with depth data versus elevation data.


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Utilizing Boring Depths vs. Boring Elevations Setting up the XDRefs, will be exactly the same as outlined above when utilizing depths instead of elevations. The main differences will be in creating labels and surfaces for use in your land development projects.

Creating Point Label Styles with Boring Depth Data When you create a point label style, you may include an equation inside of the braces of the label contents. In this way, you may label the actual elevation of the boring strata by subtracting the boring depth from the point elevation. The equation will look something like this:

Topsoil El: {Elevation-XDREF=Boring-TopSoilDepth}

Creating Surfaces with Boring Depth Data In order to create a surface with boring depth data instead of strata elevations, we will utilize both Land Desktop and Civil 3D.

Utilizing LDT, we can create a surface from the depths just as we created the surface from the elevations. We’ll simply set up the XDRefs and point group overrides and use the point group for our surface data.

In order to create a surface to use for cross-sections, volumes and profiles, we’ll need to basically subtract the boring depths from the existing ground elevation. We can easily do that with volume surfaces such as the composite method in LDT; however, volume surfaces may not be used in LDT for sampling cross-sections, volumes, and profiles.

Autodesk Civil 3D 2004 has the ability to create a surface like the composite method in LDT. The TIN Volume surface in C3D compares two surfaces to each other. We’ll use this method to create our strata elevation surfaces for use in LDT.

Exchanging data between LDT and C3D is quite easy with the use of LandXML. We can use LandXML to share point data, alignments, parcels, and surfaces between LDT and C3D. If you’d like more information on the origins and use of LandXML, visit www.landxml.org.

Sharing LDT Point Data with C3D 1. Create a point group in LDT as described above with ledge

depth overrides from the XDrefs, i.e. Borings-Ledge Depth

2. From the Projects pull-down menu, select Export LandXML…

3. Check the selection box next to Points and select the Points… button

4. Select the By Point Groups radio button

5. Highlight the Borings-Ledge Depth group

6. Select OK

7. Select Export

8. Nagivate to an appropriate storage location and give the file a descriptive name

9. Select SAVE

10. Open Autodesk Civil 3D

11. Create a new drawing utilizing a Civil 3D template

12. From the General pull-down menu, select Import LandXML…


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13. Select OK

14. In Prospector, the Point Group “All Points” should be updated to reflect these new points. If it is not, simply right-click and select Refresh.

Sharing LDT Surface Data with C3D 15. In Prospector, expand the drawing tree to Surfaces

16. Highlight Surfaces

17. Right-click, select Import TIN…

18. Navigate to your LDT existing ground surface .tin file and select OPEN

19. In Propsector, highlight Surfaces

20. Right-click, select New…

21. In the Create Surface dialogue, use the Type drop-down list to select TIN surface

22. Name the surface appropriately, i.e. Ledge Depth

23. Select OK

Now both the existing ground surface and the ledge depth surface should appear in the Prospector tree. Prospector allows us to access all of the data in our drawing and perform many actions on the data through the use of right-click menus. In addition, the existing ground surface should be visible in the drawing area. Next, we will add the data that defines the ledge depth surface, and, then, we will create the comparison surface that is actually our ledge elevation surface.

24. In Prospector, expand the full tree for the Ledge Depth surface

25. Highlight Point Groups

26. Right-click, select Add…

27. Select the All Points group

28. Select OK

29. In Prospector, highlight Surfaces

30. Right-click, select NEW…

31. In the Create Surface dialogue, use the Type drop-down list to select TIN volume surface

32. Name the surface appropriately, i.e. Ledge Strata from Depths

33. The base surface will be Ledge Depth

34. The comparison surface wil be Existing Ground

35. Select OK


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The selection of the surfaces may seem a little backwards to users who normally use volume surfaces to calculate earthwork. If you think carefully about what we are trying to accomplish, this order makes sense. We are looking to generate a surface with positive elevations for the ledge strata.

If we subtract the positive ledge depths from the positive existing ground elevations, the result will be “cut” or negative elevations.

If we subtract the positive existing ground elevations from the positive ledge depths, the result will be “fill” or positive elevations.

When we created a surface of the boring depth data in LDT, we had straight line averages of the depths between those points. The TIN Volume Surface in C3D is much like the Composite Volume Surface in LDT and makes a comparison of every point on each surface to each other. At each location on the existing ground that we do not have a comparable boring, the composite method will compare to that average depth. Summed up mathematically, the equation that we will use will look something like this.

AvgDepth - EG = Extrapolated (Average) Ledge

We “subtract” the existing ground from the ledge depth surface utilizing the TIN volume method. This gives us a volume surface representing the average elevation of the ledge strata.

When we used the ledge elevation data earlier, we had straight line averages of elevations for the ledge strata between our boring locations. By utilizing the depth data and the TIN volume method, the ledge strata has been extrapolated to mimic the curvature of the natural ground surface!

Let’s take this data back to Land Desktop.

Sharing Civil 3D Data with Land Desktop 36. From the General pull-down menu, select Export LandXML…

37. Type “f” at the prompt to select Filter

38. Check the box for the Ledge Strata from Depths surface

39. Select OK

40. Chose a descriptive file name for storing the .xml file

41. Select SAVE

42. Switch to Land Desktop

43. From the Projects pull-down menu, select Import LandXML…

44. Navigate to the .xml file

45. Select OPEN

46. Select OK to allow LDT to browse the .xml file and compare it to the existing project data

47. The comparison should show one new surface available for import

48. Select OK

49. Select Import

50. The new surface should now show up in your Terrain Model Explorer

51. Update the cross-sections Multiple Surface selection and view all of the data that we have created

Existing Ground

Ledge Strata from Boring Elevs

Ledge Strata from Boring Depths

Ledge Depths


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Summary Autodesk Civil Solutions offers a complete solution for working with point data such as geotechnical information and utilizing it in a design environment.

In this workshop we concentrated more on the point management, point labeling, Autodesk Map 2004 integration, and developing terrain models from the geotechnical data with Autodesk Land Desktop 2004. We looked briefly at the new tools in Autodesk Civil 3D 2004 that allow us to manage surface and point data. Managing these types of data is the foundation for developing a design based on intelligent decisions referencing all known information on a project.

About the Speaker: For the past 3 years, Shawnita has worked as a civil applications engineer at Autodesk helping engineers in the United States find appropriate design solutions through technical demonstrations, seminars, and workshops. Prior to joining Autodesk, Shawnita worked for 7 years as a civil engineering consultant using Autodesk® solutions in residential and commercial subdivision development projects. With a primary focus on grading and drainage design, her experience also includes utility planning, roadway design, traffic analysis, and surveying.

Shawnita Sterett, P.E. Applications Engineer Infrastructure Solutions Division Autodesk, Inc. [email protected]

Acknowledgement: Portions of the Land Desktop sections of this paper were adapted from “Managing Geotechnical Data with AutoCAD Land Development Desktop” of “Autodesk Land Development Solutions Customer Application Spring Workshop 2001” written by Toby Jutras, Applications Engineer for Autodesk, Inc. Many thanks to Toby for the use of his excellent document!