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- Posts: 3503
- Joined: Thu May 22, 2008 5:45 pm
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- Location: Hillvale, Isle of Dawn
So far, I have a way to calculate first a rotation (measure the XY position on two identifiable points on each map, calculate the angle on each image, and rotate to correct for the difference), and then a resize factor (measure the XY length of a box that covers two identifiable points on each map, calculate the width and height of the box on each image, and resize accordingly; this may involve different vertical and horizontal factors).
However, I have realised that where the map is significantly removed from both the zero latitude or the zero longitude, there is an additional "shearing" distortion. Does anyone know how to calculate a correcting factor for this?
- Posts: 2318
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- Location: Akita, Japan
I would just use a program to reproject and be done with it. G.Projector comes to mind.
- Frost Giant
- Posts: 860
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- Location: Denver, CO
This tends to happen anywhere scale factor moves further away from 1:1, whether the base map or the projection/projected map (in your case new map) is the one that is "smaller" in scale or more distorted.
But Thorf's suggestion is sound...assuming they are equirectangular maps. Are they?
"You stumble into a spacious chamber with at least ten exits." The DM is a jerk. --Jeff Rients from Jeff's Gameblog