ProcLib

Title: Digitizing Data from an Aerial Photograph (ArcMap 10)

Purpose: The following proclib is for digitizing important data from an Ariel photograph or other image data into a new shape file. This is a means of abstracting important information from an image file and turning it into a feature or vector shape file for later use in a GIS database. One example of its use would be to bring field data that can be recorded on an air photo into a study database.

Procedures:

Part 1: Building an empty shape file for storing your work in

1.  Starting: Turn on ARC-CATALOG

Make sure that the Catalog Tree appears in the left hand window on the screen, if not click on the Catalog Tree window icon as indicated below.

a.  Then in the Catalog Tree, set the file to the U Drive (or your thumb drive or elsewhere to save your work)

2. Folder Creation: From the menus choose File-New-Folder

  1. This is where you will place your work, give it an appropriate name

2.  Shape File Creation: again from the menus choose File-New-Shapefile

  1. In the window that opens provide
  2. Name for the new shape file
  3. Feature Type – choose between point, polyline, or polygon
  4. Coordinate System – this is where you choose the coordinate system for you your final file – in our example it will be State Plane (see figure on next page)

1.  Click EDIT

2.  Click SELECT

  1. Projected Coordinate Systems
  2. State Plane
  3. NAD 1983 (US feet)
  4. Washington North
  5. Add
  6. Apply

3.  OK

CAUTION Do not use: NAD 1983 (2011) (US Feet)

Part 2: Loading the shape file with points, lines, or polygons of data (entities)

1.  Starting: Turn on ARC-MAP as a blank map

2.  Add an Ariel photograph: using the + icon add data (here we will go to j:/geo/geodata/Bham/Ariel_photos/2008color/380331SW.jpg

  1. To add data first CLICK ONCE AND ONLY ONCE on the file name
  2. Then in the window the opened click on ADD
  3. If you don’t do the one click and add the image will only come up in BW format instead of color
  4. Using Zoom and Pan tools move to the appropriate area to be digitized

3. Add the new shape file to TOC: From you work above add the new shape file into which you will put your digitized data. (again use the + icon)

4. Click the box next to the new Shape File to make sure it is active. (If this is not done, digitizing won’t work)

5. Add edit tools (if necessary): From the menu select Customize – Toolbars—Editor then place it at a convenient place near or on your Data View

6. Start Editing: from the Editor Toolbar select the arrowhead icon next to the word Editor and scroll down to Start Editing then click. A window will open to the right of the screen with the file name to be edited.

7. Zoom in to the area that you want to do your digitizing on, be careful that you don’t get too much pixilation. Then…

8. On the right hand side of the screen under Create Features click on the shape file name and note that the Construction Tools should identify the correct entity (point, line, or polygon) at the bottom of the window. Go down and click on that entity name to make sure it is active.

9. Now move over the aerial photograph and you should see a hollow arrow, then click wherever you wish to place an entity (points will appear as circles with crosses in them, lines as lines, and polygons as a self-closing figure)

1.  Once you are done you can Save Edits and/or Stop Editing.

Part 3 Working with Additional Files – to use these steps make sure that you have clicked STOP EDITING (if you didn’t then do so before proceeding, if you don’t then things will work differently and these steps won’t be correct).

1.  Make a new shape file in ArcCatalog (for example a Polygon shape file) as we did above.

2.  Using Add Data put the additional shape file(s) in your TOC and click their box to make them active.

3.  Start Editing by clicking that command in the Editor toolbar (as you did before)

4.  The following window will open in ArcMap

5. We will double click on the new shape file (our new polygon one in this case to

continue).

6. Once the Create Features window opens click on the file name then correct tool (in our case Polygon)

7. By moving the cursor over the photograph a black cross outlined in white will appear. This will work like an elastic cord. Go to the object you want to capture as a polygon. Click once to start, and then click each time you want to go around a corner or change directions. When you are double click. In the image below you will see that a polygon outline in blue (showing it is active) should now appear. If you like the result you use the Save Edits under the Editor tool.

8. You can now continue to capture more buildings as polygons or stop editing and add additional new shape files to digitize more information.

Originator: p. buckley

Date created: Feb. 10, 2012

Contact email:

ArcCatalog & ArcMap Digitizing Proclib Page 8