DEM from contour lines

[Guest thrimur]

Hi, as elevation data doesn

[Holger 0]

Hi thrimur,you're the first that I know of who used Blackart' contour-to-DEM features to make an FS mesh - consider yourself a pioneer! ;-)You say that you import your Blackart output into MicroDEM. The Analyze-Header function in MicroDEM should give you the correct X and Y spacing and column/line information to use in the inf file. Further, the Map Window Corners function should give you your correct NW corner coordinates. Have you tried using those data?Cheers, Holger

[Guest thrimur]

Hi Holger,And it felt just like I where a pioneer, cutting through thick bushes of a rain forrest when I spent hours after hours cleaning up the contour lines and figuring out the numbers of iterations to use to get decent dem without paralizing my computer.Then the trouble started, because I didn

[Guest sgreenwood]

Hello Thrimur,I'm not sure what may be causing the distortion, if you are referring to some effect other than the omission of some source data. As for "the parts of the dem was always missing in tmfviewer", this is typical. Unless you have carefully created the DEM with boundaries which coincide with the boundaries of the underlying grid for the LOD you select, Resample will omit data along one or more edges. I have more details about this isssue at:http://www.fs-traveler.com/mesh-gaps.shtmlSteve

[Guest thrimur]

Hi Steve, I read your article. Is this non lod-fitting data the reason I can

[Guest sgreenwood]

Probably. Here is the information my LOD calculator (available from my site) provides.http://forums.avsim.com/user_files/81436.gifIt looks like LOD11 is the smallest you can use with your data. Higher LOD values will use a bit more of the data, but not all of it.Column "Area Covered(1)" shows the subset of your data that will be converted to mesh at LOD11. Column "Area required(2)" is the smallest amount of data you must provide to insure your source coordinates are included in the mesh.Steve

[rhumbaflappy 113]

Hi thrimur.Why not post the INF file you are using, and tell us what version of resample you are using?As long as the source file is 16 bit, little-endian, we should be able to compile a BGL. The actual source elevation really isn't needed for us to recreate what you are getting.Dick

[Guest thrimur]

Hi, I now see why the lower part of the dem is missing, it now shows up just like Steve

[Guest thrimur]

I changed the coordinates of the dem slightly, and when I ran it through read_dem I saw two kinds of datum: vertical datum NGVD and horizontal datum WGS84. Does the vertical datum have to be WGS84 also? if yes how do I change it?I just want to get this to show correctly before I start filtering out contourlines of bigger maps.thrimur

[rhumbaflappy 113]

Hi thrimur.I don't believe the vertical datum will make any great difference, as long as sea level is expressed as 0 meters, and the elevation for each point is expressed as meters.If your resample is multiplying the data by ten, try:ScaleInMeters = 0.10to reduce the elevations by a factor of ten.Dick

[Guest sgreenwood]

"I downloaded your LOD-calculator Steve, if I key in the coordinates 64.1650 it changes to 641.650 when I press enter (I haven

[Guest thrimur]

Hi, When saving ASCIIdem with blackart you are presented with three options: Planimetric units code 1,2 and 3 and elevation units code 1,2 and 3 I am not sure what they stand for but if I use any other planimetric code than 2, 3dem doesn

[Guest thrimur]

I downloaded full install of microdem, now everthing works fine, microdem now shows correct coordinates, in/out button works. It