Issues with both Microdem and transdem

[alpha11]

I just started a new route and I have tried both Microdem and transdem to create my maps

Microdem make really good maps, but every time try to complete the tiger data I get an bit map not valid or system resource error.

PC:
Intel 8400 @ 3gh
4 GB Ram
8800 GT video card

Transdem is really nice to work with, but the heigh of the hills is not correct since I know the terrain very well on the route.

How can I fix either program?

 

[geophil]

Transdem is really nice to work with, but the heigh of the hills is not correct since I know the terrain very well on the route.

Can you explain this a bit? Which DEM data source are you using and which map or ortho photo source?

 

[alpha11]

I'm using dems from this link ftp://e0srp01u.ecs.nasa.gov/srtm/version2/SRTM3/North_America/

And MS maps

 

[geophil]

Right. This is SRTM 3 arc sec data. For projects outside the US or Canada SRTM 3 arc sec is possibly the best free DEM you can get but for the US I would go for USGS DEMs instead, NED in particular.

MS Maps? You mean maps.live.com aka MS Virtual Earth? Or USGS DRG topo maps via MS TerraServer? Both have their pro and cons. Virtual Earth is based on road maps and railroad lines have limited resolution and may not be too accurate. MS Terra Server has some maps with georeferencing errors.

For your project the question is: Which is the erroneous data source? The DEM or the map?

 

[alpha11]

Thanks

Hugh inprovment with NED 1/3, now all I need is Transdem for 2009