Hi, I've been able to make some fairly accurate plots, but I'm still off. Please check my understanding and method.
Here are my conversion parameters in Proj.4 notation:
+proj=longlat +ellps=WGS84 +datum=WGS84
+proj=lcc +lat_0=85 +lat_1=20 +lat_2=60 +lon_0=-98 +x_0=0 +y_0=0 +units=m
+a=6378137 +rf=298.257223563 +no_defs
Northing seems to be 0 at lat 85, lon -98. The map looks like a fan, and that's the corner. Northing becomes more and more negative as latitude decreases.
Easting seems to be relative to lon -98. It's positive on the east side and negative on the left.
When I plot a point in my image, how do I decide how many pixels there are per meter? My map image's left and right edges are approximately lon -129 and lon -76 respectively. Its top and bottom edges are approximately lat 60 and lat 20. To calculate the number of pixels per meter of easting, I have been using the number of meters between the points of the lower two corners, -129/20 and -76/20. This seems to work somewhat, but I doubt it's the correct way to do it.
Thanks for any help!