Comments on: GDAL-based DEM utilities

By: Paolo V.

Paolo V. — Wed, 02 Jun 2010 23:31:55 +0000

This little and powerful toolset saved my day!
FWTools do not have gdaltodem , and they are not updated either.
Compiling Gdal on my system is not possible: process is failing after some time.
I was looking for a linux batch mode for creating a raster image of a dem file, and here I found the solution.
THANKS!

I suggest TIFF Tools for linux, and ImageMagick, plus the pnm tools for conversions.

slope src.tif dst.tif
tifftopnm dst.tif >dst.pnm
pnmtojpeg dst.pnm >dst.jpg

as a workaround to convert into jpeg, because the “convert” tool for TIFF complains.

Overall, when someone wants to deal with rastering a dem and creating an image of it from linux he has to know that this process is not straightforward nor this simple, because tools involved are complicated , require compiling etc.

*except THESE tools*

By: perrygeo

perrygeo — Wed, 31 Mar 2010 18:16:06 +0000

Gabriel,

The color-relief program does not actually do any shaded relief/shadowing at all. It just assigns colors based on the raster value. You can generate a hillshade map separately and combine them using some of the options discussed in this comment thread (I’m sure there are other ways as well).

By: Gabriel

Gabriel — Wed, 31 Mar 2010 18:11:28 +0000

Dear Matthew

Please, could you tell me what kind of color ramp and shadow relief image combination algorithm are you using in your color-relief program?

The problem is common GIS programs usually use a difference or addition algorithm and resulting images look dull but I ‘ve seen an image example at http://wiki.openstreetmap.org/wiki/HikingBikingMaps produced by your program and it looks with nice colors and balanced shadows. It is seems your program conserve color tones and shadows.

Thanks in advance for your help

By: David

David — Tue, 30 Mar 2010 21:27:31 +0000

To compile on ubuntu 9.10 I did:
g++ `gdal-config –cflags` hillshade.cpp -o hillshade `gdal-config –libs`
etc.

By: fab

fab — Fri, 22 Jan 2010 09:10:48 +0000

Do you know the free software SpacEyes3D Viewer / DEM tool box, it’s a graphic interface based on gdaldem that allows to easy handle all gdaldem tools with a friendly QT interface, including a realtime preview (windows only).
http://technology.slashgeo.org/technology/09/10/29/1632224.shtml

By: Lux7

Lux7 — Mon, 18 Jan 2010 18:54:04 +0000

Hi,

using : nv 0 0 0 I dont’ see blue sea yet. It is still green
Further suggestions ?

By: Thanhlv

Thanhlv — Thu, 14 Jan 2010 06:09:05 +0000

Ops, for blue color:
nv 0 0 255
right?

By: Thanhlv

Thanhlv — Thu, 14 Jan 2010 06:08:21 +0000

@Cecilia
Just simply add to the end of color text file this line:
nv 0 0 0

By: Cecilia

Cecilia — Mon, 11 Jan 2010 13:37:52 +0000

Hi!

I’m using GDALDEM utilities from FWTools shell and I want to make a DSM color relief based on a color text file.

But I’m having problems in aplying the color blue only to “NoData” pixels.

This is the color table that I’m using:

nv 148 184 235
0 137 90 68
5 76 115 0
10 38 115 0
20 76 92 0
50 17 69 17

What can I do to solve this problem?

Should I classify the noDATA pixels to a specific number like “99″…

Thanks

Cecília

By: Lux7

Lux7 — Fri, 08 Jan 2010 18:20:58 +0000

hi,

Why I see the sea green ?
I have added the line

0.1 50 180 50
0 0 0 255

in the scale.txt

Thanks