Troubles in Gradient values

[Dzmitry Yablonski]

Hi all,

I m trying to calculate Slope Gradient with https://code.google.com/p/jgrasstools/wiki/Gradient .

The final picture has good general quality with comparation of QGIS calculation.

But the values are very strange. Range of values from 0 to 6800+ that means the Gradient is close to 90 degrees.

The area elevation difference is 20m between the lowest and highest points.The area size is 1800 x 2400 m2 and it's more less flat.

My sources to calculate gradient is below:

Pitfiller pitfiller = new Pitfiller();
pitfiller.inElev = elevationCoverage;
pitfiller.pm = progressMonitor;
pitfiller.process();
GridCoverage2D pitfillerCoverage = pitfiller.outPit;

Gradient gradient = new Gradient();
gradient.inElev = pitfillerCoverage;
gradient.pm = progressMonitor;
gradient.pMode = 2;
gradient.doDegrees = false;
gradient.process();
GridCoverage2D gradientCoverage = gradient.outSlope;

Elevation data is in meters.

Can you help to find the solution to amend to more correct values ?

I use JGrassTools version 0.7.6 and also tried 0.7.8 with the same result in values.

Many thanks,

Dzmitry

[Silvia Franceschi]

Dear Dzmitry,

did you tried to use the original DTM instead of pitfiller? did you checked the values inside the pitfiller map?

If you still have problem you can send privately to me the data so I can test it on my PC.

Regards

Silvia

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[Dzmitry Yablonski]

The issue was resolved.

I used  projection EPSG 4326 instead of metric projection (concrete UTM zone as EPSG code).

After conversion coordinates to UTM i got valid values in range from 0,005 to 0,032.

Thanks to Silvia for her support.

Best regards,

Dzmitry

четверг, 3 декабря 2015 г., 10:36:34 UTC пользователь Dzmitry Yablonski написал: