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Analysis in 9.0
What’s Next
• To be really accomplished in GIS (or GIT) you need the following …– Vector GIS (You got it)– Raster GIS (FOR556)– Expert in Vector GIS (FOR558)– GPS FEG XXX– Remote Sensing FEG XXXXXXX– Database management (FEG xxxx)
For Science & Engineering
• Biology – Raster and Vector …For556 and Myra Hall’s xxxx (final project can be same for both)
• Landscape Architecture – Vector GIS (FOR558) and AutoCad
• Forestry – Vector GIS (FOR558 & 556)
• Engineering (see previous slide)
For556, Spatial Modeling• Use IDRISI to solve problems dependent on
continuous surfaces ( elevation, water table, viewsheds, etc.)
• Emphasis is NOT on learning the software – that is easy
• Emphasis is on Creative Thinking through applying the technology to problem solving
• Like 557 has weekly exercises that provide less cookbook instructions as the semester progresses
• Quizzes but no exams; final problem
FOR558 Advanced Topics• Next semester will be ArcGIS
• Emphasis on– Editing vector data – a tricky business
in ArcGIS– Analysis– Using Data Models like
• ArcHydro for hydrologic modeling• Forestry Data Model for forest
management• Planning Data Model
– Grid processing and modeling
The latest and greatest
development in GIS
FOR558 Advanced Topics• Next semester will be ArcGIS
• Emphasis on– Editing vector data – a tricky business
in ArcGIS– Analysis– Using Data Models like
• ArcHydro for hydrologic modeling• Forestry Data Model for forest
management• Planning Data Model
– Grid processing and modeling
Small class – exact topics covered depends of interests of enrollees
Sales Pitch Over
On to
Analysis
In 9
Analysis
• Possibilities are the same as AV3.3– Select by Attribute (Query Builder)– Select by Location (Select by Theme)– Overlay Analysis (GeoProcessing Tools)– XTOOLS (XTOOLS)
(but not the same xtools!)
Selection
IMPORTANT!
Selection Options• Lots of
control of how features are selected
Select by Location
Same stuff as AV3 but use is a little different
Select by location Options
Select Features from
Add to the currently selected features in
Remove from the currently selected features in
Select from the currently selected features in
Select by location Options
Lots of choices here -- and they all do slightly different things
Pick your layers here
Here are some actions…
• Watch the bottom of the dialog and make sure it is doing what you want it to
• That sounds easy but quite often NOT easy
• Here are some of the options
Options:Intersect
Options: Intersect
Options:Touch Bndy of…
Options: Have their Center in…
Options: Are completely w/in…
Options: w/in a distance of…
Options: are contained by…
Overlay Operations
• Overlay operations are like the “select by location” functions but not the same.
• Both use two layers– Select by location just selects
features– Overlay operations create new
feature classes
Toolbox
Overlay: Erase• From Help: Erase feature removes a chunk of
the input feature• It is important to keep Input and Erase feature
correct or GIGO
Overlay: Identity• Computes a geometric intersection
(logic) of the input and identity features• Input features (or portions thereof) that
overlap the identity features will get attribute features from the identity features
• To put it another way: combines the portions of features that overlap the identity features to create a new feature class.
Overlay: Identity• Computes a geometric intersection
(logic) of the input and identity features• Input features (or portions thereof) that
overlap the identity features will get attribute features from the identity features
• To put it another way: combines the portions of features that overlap the identity features to create a new feature class.
Clips by the Input feature and then UNIONS what is
left.
Overlay: Intersect• Computes the geometric
intersection of the input features or portions of features COMMON to all layers.
• This tool builds a new feature class from the intersecting features common in both feature classes. Available with any ArcGIS license.
Overlay: Intersect• Computes the geometric
intersection of the input features or portions of features COMMON to all layers.
• This tool builds a new feature class from the intersecting features common in both feature classes. Available with any ArcGIS license.
Intersect is NOTthe same as
Identity
Overlay: Symmetric Diff
• Computes a geometric intersection of the input and update features. Any features COMMON to ONLY one of the inputs will be written to the output
• Or to put it another way: This tool creates a feature class from those features or portions of features that are not common to any of the other inputs.
Overlay: Symmetric Diff
• Computes a geometric intersection of the input and update features. Any features COMMON to ONLY one of the inputs will be written to the output
• Or to put it another way: This tool creates a feature class from those features or portions of features that are not common to any of the other inputs.
This is the olive drab feature showing
through a hole in the yellow feature!
Overlay: Union
• This computes a geometric intersection of the input and output feature classes . ALL features will be written to the output feature class with the attributes from both.
• Or: This tool builds a new feature class by combining the features and attributes of each feature class.
Overlay: Union
• This computes a geometric intersection of the input and output feature classes . ALL features will be written to the output feature class with the attributes from both.
• Or: This tool builds a new feature class by combining the features and attributes of each feature class.
UNION: another view
Overlay: Update
• Computes the geometric intersection of the input and update features. The attributes and geometry of the input features are replaced by the update features.
• This tool updates the attributes and geometry of an input feature class or layer by the Update feature class or layer that they overlap
Overlay: Update
• Computes the geometric intersection of the input and update features. The attributes and geometry of the input features are replaced by the update features.
• This tool updates the attributes and geometry of an input feature class or layer by the Update feature class or layer that they overlap
Overlay: Summary
IDENTITY INTERSECT SYM-DIF UNION UPDATE
Summary
• The analysis tool in ArcGIS are very powerful
• And fairly easy to understand … one at a time!
• It is the combining of the overlay and selection tools to solve a problem that is the problem!
Sewbuf300
BufferSewersw/in 300m
Streamsnot w/in
20m
SewerOKERASE
Landuse:brush
lucode=300
SoilsSuit > 2
Strmbuf20
Buffer
OK sitesIDENTITY
Land OKIDENTITY
Of selectedpolys
Query
Query
Sel by Theme: Intersection
• Intersected Parcels w/ Cover with Ag Selected
• The red outlines are the selected parcels
Lets Zoom In ----
Select by theme
• You can see that• Entire Parcels
were selected• Parcels with only
a little bit of Ag landuse were selected
Overlay Intersection• BUT THE RESULT IS VERY DIFFERENT!
Red outlines are the parcels selected by Select by theme
Green are the result of the Overlay
So you have to be careful!
• Exercise 6 has you experiment with some simple layers
• And I will be throwing some relatively simple problems your way to provide more practice
• And I will be changing the schedule at bit too.