Bob, Mr Video that is very interesting about sectional error being "built in". The project that I'm working on is a GPS unit that I'm considering building from parts. Some history of the project is that over the last Summer I became involved in another project of building a CNC machine. While researching the workings of CNC I came to realize that a CNC machine is really nothing but a stationary auto pilot. That got me thinking, What if? As it turns out it's not that far out of the question to build your own flat screen avionics suite, and fairly inexpensively at that. However, as this project has progressed I have become intrigued by maps of the calibrated variety. To date I have calibrated One partial sectional with a small degree of success. With a scanner I've created a three image scan of part of a sectional. In Photoshop they were stitched together very carefully to create one image then used Pixillon image converter to save that .jpeg as a .ras. I then used a third program to calibrate the co-ordinates to create a new calibrated partial sectional. Problems that become apparent in this process are mostly centered on the fact that sectionals are created as Lambert Conical Projections. Maps used for GPS are calibrated with WGS84 co-ordinates and tend, it appears, to be for all intent and purposes' flat images of only several miles on a side which are tiled together as you zoom out of your image collection. The partial success that I mentioned came mostly, I believe, as a result of the Lambert Conical projection used in the original chart. Having very carefully located and placed the calibration points used once the map was calibrated and saved I found an error of about 7/10ths of a mile centered right about the middle of the chart which agreed fairly closely by direction and distance with the distortion from the original sectional. The width of the map as calculated by the calibration program was 40,000 meters. JG
