Author Topic: MyTopo/Color and MSR Topo/B&W layer registration?  (Read 5031 times)

Rick Kunath

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MyTopo/Color and MSR Topo/B&W layer registration?
« on: July 03, 2010, 08:36:28 AM »
I'm not sure if this belongs in the Beta forum, I just registered today and an using the newly released 4.0 version, which I am assuming is a permutation of the last beta. I hope to be testing the beta releases too, so I will contribute when I can.

I am noticing a layer registration issue that seems odd. I was looking at a fairly close zoom of a portion of Canyonlands National Park's southern boundary in the Cathedral Butte area. What I am seeing is that the MSR topo maps and the black and white aerial photos line up perfectly when you switch between them. Also the color and Utah alternate color aerial photos line up perfectly with the MyTopo maps. But if you switch between the MyTopo and MSR topos you get a jump in the display, the same is true for the black and white and color aerial photos.

There are points in the map that do line up, but in watching the aspect ratio, it seems as if the color and MyTopo layers are somehow distorted by being zoomed in the horizontal direction. Vertical alignment seems darned close. The central point alignment on the screen of the layers is close, very close, but as you get farther from the center point in the horizontal direction, the registration errors get worse. Vertical seems darned close across the layers.

At first I thought this had something to do with the rectangular shape of the MyTopo maps, but they show the same way on their web page as they do in TopoFusion. And the color layer behaves this way too.

I'm using a 20-inch high-end Viewsonic 4:3 aspect ratio LCD monitor driven by a fairly high end nVidia card via DVI and the latest drivers.

I attached a few waypoints to show the issue.

Loving the new 4.0 release.

ScottMorris

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Re: MyTopo/Color and MSR Topo/B&W layer registration?
« Reply #1 on: July 03, 2010, 01:50:06 PM »
Thanks for the feedback on v4.0.  What you are seeing is a difference in map projection.  The old MSRmap topos are in UTM projection, while most other map types (color, myTopo) are in a 'geographic' (lat/lon) projection.  So, not only do the maps change, but any tracks and waypoints displayed will 'stretch' as you switch back and forth.

The new combo mode can combine all types of maps, by changing the projection.  In a future version we may settle on one projection and simply do the re-projection like the combo mode does.

Thanks!
Scott Morris - founder and co-author of TopoFusion
email: smorris@topofusion.com