The chosen control map is "blocks.shp". It was in Massachusetts State Plane projection with map units in feet. I converted it to Mass. State Plane, meters using the "change projection" command of the Projector! extension. I also edited the legend to show outlines instead of filled polygons to better align the maps.
 

Rectifying an aerial photograph with an unknown (presumed non-orthagonal) geometric referencing system to a known system.

I rectified the image "airphoto.tif" using the Image Warp extension. I opened the Image Warp session using "airphoto.tif" and "blocks1.shp" (the reprojected control map). I chose 4 control points at corners of blocks near the American Repertory Theater, the focus of our study. A hard copy of the table where Image Warp records the GCPs chosen is attached.

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I calculated Root Mean Square Error for a 1st order transformation, and created the new image. Image Warp created an error report for this transformation :

GCP ID  Input X            Input Y            Output X           Output Y           X error            Y error
_________________________________________________________________________________________________________________
001     000000000002.046   -00000000001.506   000000231184.198   000000902672.431   -00000000000.783   000000000000.896
002     000000000001.375   -00000000001.731   000000231030.278   000000902629.059   000000000000.845   -00000000000.966
003     000000000001.575   -00000000000.266   000000231102.714   000000902966.417   000000000000.702   -00000000000.803
004     000000000000.871   -00000000000.615   000000230935.853   000000902898.288   -00000000000.764   000000000000.873
_________________________________________________________________________________________________________________

Total X RMS Error = 0.7751720 in Output Map Units.
Total Y RMS Error = 0.8864740 in Output Map Units.
ChiSquare X Error = 2.4035690
ChiSquare Y Error = 3.1433460

Rectifying a scanned map with an unknown (presumed non-orthagonal) geometric referencing system to a known system.

I registered the scanned image "zoning.tif" using Image Warp with "blocks1.shp" as reference.  I used same GCP table as the earlier transformation to use same 4 control points and moved the control points into the right positions on "zoning.tif" image. Image Warp made the appropriate changes in the GCP table and a hard copy is attached. After calculating RMS error I executed a 1st degree transformation. The error report for this transformation was :

GCP ID  Input X            Input Y            Output X           Output Y           X error            Y error
_________________________________________________________________________________________________________________
001     000000000005.455   -00000000003.745   000000231184.198   000000902672.431   -00000000000.258   000000000000.676
002     000000000004.590   -00000000004.758   000000231030.278   000000902629.059   000000000000.276   -00000000000.726
003     000000000003.716   -00000000002.241   000000231102.714   000000902966.417   000000000000.229   -00000000000.600
004     000000000002.881   -00000000003.487   000000230935.853   000000902898.288   -00000000000.247   000000000000.649
_________________________________________________________________________________________________________________

Total X RMS Error = 0.2530780 in Output Map Units.
Total Y RMS Error = 0.6644230 in Output Map Units.
ChiSquare X Error = 0.2561930
ChiSquare Y Error = 1.7658310

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Heads up digitizing

To create a polygon shape file for trees in the area, I created a new theme and used the circle tool to draw the location and diameter of trees that I could see on the aerial photo. This method for creating a data layer is bound to have large errors because the aerial photo already has some error and human error and the inclarity of the photograph will compound it.

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The registered scanned zoning map was used to create a polygon shape file by drawing over the image and entering zoning data into its attribute table. The digitizing involved drawing a polygon for the whole boundary, splitting it into smaller polygons and subtracting features to remove overlaps. I edited the legend to use transparent backgrounds to be able to see the overlay clearly and the unique values have different colours.

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Registering an unknown (presumed orthagonal) geometric referncing system of an Autocad drawing to a known system.

I registered the Autocad file "buildings.dxf" by using the lines and polygon files. I used the Cadtools extension to make a world file by picking 2 points (affine) at the corners of buildings near the ART and using the aerial photo as the reference.  The world file look like this :

4394.09,-2353.7 231185,902673
3723.54,-3191.16 230933,902874

I used the same world file for both shape files and they were moved to the correct position. I converted them to shape files and edited the legend to transparent backgrounds to see the underlay.

Converting GIS export formats

I downloaded the wetlands information in GIS Export format (*.e00). Using Import71, I imported them into Arcview format. It created a folder for each export file with a polygon, a line and a point theme each. I added all these themes and "changed projection" using the Projector! extension from UTM '27, zone 19 to Mass. State Plane, meters. I edited the legend to show unique values of various classes of wetlands. Our study area has no wetlands in it.