Pat, I would like to thank you for realy useful information. During, last two days I have been trying to use all of above information in order to recreate small portion of terrain. Unfortunately, I haven't succeeded yet as I am probably doing something wrong.
Quote:
Originally Posted by Patrick Proctor
Use the info function to get the grid transform angle. That angle will be in degrees, which you can convert to mils.
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In MicroDem function "Map information" gives following:
True north at top of map
DEM native datum: WGS72
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Magnetic declination: 3.5°
UTM Grid declination: -1.2°
At the same time function "Horizontal Earth Curvature" provide:
Point: N43°46' 0.01" E18°58' 0.00"
Grid true angle: -1.56
I noticed that -1.2° (-21.3 mils) is some kind of average for whole map area, while -1.56 (-27,7 mils) is value for bottom left corner of map. Also, with function "UTM-grid true north declination" it is possible to get value for exact spot on map (for example -1.54). I hope that these are "grid transform angle" values you have mentioned before. If so, I presume that best measure is one obtained through "UTM-grid true north declination" for map area I want to recreate. Right?
Nevertheless, I tried all of mentioned values on my map but resulting AATF contour map doesn't match Google terrrain map and there is always some discrepancy. If I entered right coordinates, mils and m/s, could there be any other reason for this discrepancy? Different map projections maybe? Also I didn't change default 8-digit UTM values and Grid Zone Designators in Map Information Dialog (as I presume that is enough to put right long. and lat. coordinates).