Mapping Gettysburg, PA – Civil War Battlefield

Learning Resources: http://techcenter.jefferson.kctcs.edu/GIS/modules/Virtual/Pages/Georeferencing.aspx

http://techcenter.jefferson.kctcs.edu/GIS/modules/Virtual/Pages/UsingHistoricalMaps.aspx

Locate Shapefiles and maps 1. Select Pennsylvania and Adams County

http://techcenter.jefferson.kctcs.edu/GIS/data/country/USA/Pages/default.aspx

2. Decompress the data and save in an appropriate location

Process

Georeferencing 1. Start ArcMap (9.3.1) 2. Click on the add data button 3. Load all of the appropriate data required, shapefiles, images, etc.

4. You may wish to project the data before georeferencing, this can be done by opening the toolbox, then by selecting Data Management Tools ---Projections and Transformations

5. Select the georeferencing tool click on – view then select toolbar and then click on editor, make sure the image layer is selected in the layer box

6. Click on the green and red plus to begin georeferencing 7. Select the first point on the historical map, zoom to reference layer and select

corresponding point, zoom to historical map and select a second point (as far as reasonable from the first point), zoom to reference layer and select the second corresponding point, map should then be referenced. Select additional points to increase georeferencing, always select the historical map first.

8. Final save the map by right clicking on the historical map and select save as a layer file so the georeferencing will be retained.

Digitization 1. To do heads up digitization of the map go to – view ---toolbar and select the editor function 2. Go to ArcCatalog and create a new layer (line), by right clicking and selecting new, select an

appropriate name for the new layer. 3. Load the new layer created above onto your map (either from ArcCatalog or ArcMap), nothing

will display since the layer is empty. 4. Go back to ArcMap and turn on the editor (you must select the new layer) 5. Select the pencil tool. 6. Digitize positions of troops; a double click will end the line of troops, some lines which are linear

will require just two points, others that are curved will require multiple points. Each feature should be in a different shapefile.

7. To create a new field in the shapefile, save your edits and stop editing, it seems strange that you must stop editing to create a new field.

8. To create new fields in this shapefile you must open the attribute table, by right clicking on the file name; create fields for identification of units, commanders, army (confederate or union).

9. Turn the editor on and select the attribute table and fill in the name of the unit, etc. in the appropriate fields.

This shapefile can be load independent of the image file in which the date was obtained from.