A Technical Discussion of the Tax Photo Geotagging Processes

Guilford County GIS & Tax Appraisal Departments

Street Level Photography Project

Eric Funderburk, GISP/GIS Analyst, Guilford County GIS

Street Level Photography ProjectOverview

Appraiser needed help processing large numbers of street level photos

No Budget to pay for a solution

Utilized “no-cost” resources

Automated Workflow

Street Level Photography Project

Processes

•Collecting Photos

•Using ArcPad to create a photo point map

•Retrieving Photos

•Synchronizing Field Data from the Mobile PC

•Geotagging Photos

•Renaming Photos by Parcel ID

Collecting Photos

Tax department staff took photographs of single-family residential structures to assess their current value

Equipment Used

Panasonic Toughbook

Trimble Handheld GPS

External GPS Antenna

Basic Point & Shoot Digital

Using ArcPad to create a photo point map

ArcPad Demo

Retrieving Photos

Automating the Image Copy ProcessOnce the SD card is removed from the camera, and loaded into the USB card reader. It is inserted into the users USB port, and is recognized by the user’s local machine. Then a python script is executed from the user’s desktop by double-clicking the "GetPhotobyDate" Icon. The script reads the SD card in the card reader, and reads the time and date that each digital image was taken. It then creates a directory on the server by date and copies the images by date to their corresponding directories.

"GetPhotobyDate"

Synchronizing the Photo Point Data from the mobile PC

The ArcPhoto Tools and Geotagging Images

The ArcPhoto Tools are a set of geoprocessing tools and ArcMap user interface enhancements to enable the quick import of digital photographs into the ArcGIS

EXIF (Exchangeable Image File Format)

EXIF Data Includes:

• Camera Type & Model

•Focal Length

•Aperture

•Flash

•Time & Date

• GPS (Latitude & Longitude)

The EXIF (Exchangeable Image File Format) data is information that is encoded into standard digital imagery. 

Geotagging Photos

Renaming Photos by Parcel ID

RenamePhotosByParcel

Renamed Photo File – r0179470.jpg

0179470

Conclusion •Reappraisal productivity at Guilford County increased immediately and dramatically.

After implementing the use of ArcPhoto into their workflow, their productivity increased at a phenomenal rate. Productivity increased from the 50 to 75 photos per day to 1500 to 2000 per day. At the end of the photo season were we able to process and geotag 75,000 images.

•Although Guilford County had no money to fund its reappraisal project, using in-house equipment and existing expertise, the tax and GIS departments collaborated and improved the daily output associated with this project.

2009-2010 Solutions AwardsSignificant Achievement In- House Collection of Street level Photographs

This project was featured in the Fall 2011 edition of ArcUser Magazine