TransDEM Forum

Hi: I am trying to get the UTM grid lines from Canmatrix Georeferenced TIF images. I downloaded the following GeoTIFF for Carcross, Yukon:

http://geogratis.gc.ca/api/en/nrcan-rnc ... 2f57f.html

When I Open the Raster image in TransDEM it does not automatically draw the coordinate grid over the image.

Strangely when I did the Tutorial 8 using the suggested Salmon Arm TIF image it did add the coordinate grid over the image! It is larger (75 Megpixels) compared to the Carcross image (only 61 Megpixels). Any help is appreciated.

Cheers,

Derek

PS: I'm using TransDEM 2.5 64bit version

Hi Derek,

well, yes.

Apparently, TransDEM is not aware of Canadian territory west of UTM zone 10 at the moment. I just figured this out analysing the geo meta data in your GeoTIFF file. GeoTIFF images use so-called EPSG codes for the coordinate systems. When I originally created my EPSG repository I started from zone 10, which is OK for CONUS, but not for Canada (or Alaska).

It's not a big deal, but hard-coded. It will be fixed in the next update.

What seems to work is the Toporama series, GeoTIFF, in geographic coordinates (not UTM, same problem there). Toporama is less detailed than CanMatrix, though. Nevertheless, this might help for the time being. Manual georeferncing should work, too, of course.

Hi Roland:

Thank you for taking the time to figure out what was going on. I will try Toporama or manual georeferencing if it is not too much work.

Needless to say I look forward to the next version.

Cheers,

Derek

geophil wrote:Hi Derek,

What seems to work is the Toporama series, GeoTIFF, in geographic coordinates (not UTM, same problem there). Toporama is less detailed than CanMatrix, though. Nevertheless, this might help for the time being. Manual georeferncing should work, too, of course.

Thank you for your suggestion. The GeoTIFFs in geographic coordinates are excellent and they have no borders so they line up correctly with the individual Canadian DEMs.

Cheers,

Derek

The same data should be available via Toporama WMS. And here UTM/WGS84 may work. WMS also relies on EPSG codes, but in this case TransDEM defines the codes. This WMS should respond to both UTM/WGS84 and UTM/NAD83 (which are identical for purposes).