[GRASS-user] r.rescale categories definition

[Aldo Clerici]

Dear GRASS Users and Developers,

I'm having some problem in understanding the categories resulting from
r.rescale 

 

With:

r.rescale in=elevation.dem from=1200,1500 to=1,2 out=elev.resc

 

I have this result:

1   1200 thru 1349

2   1350 thru 1500

 

Two categories with a range of 150 meters each.

 

But with a new three categories subdivision:

 r.rescale in=elevation.dem from=1200,1500 to=1,3 out=elev.resc

the result is:

1    1200 thru 1274

2    1275 thru 1424

3    1425 thru 1500

 

The first and last categories have a range of 75 meters and the second one
of 150 meters. 

 

Similar result with a four categories subdivision:

r.rescale in=elevation.dem from=1200,1500 to=1,4 out=elev.resc

 

1    1200 thru 1250

2    1251 thru 1350

3    1351 thru 1450

4    1451 thru 1500

  

Categories 1 and 4 have a range of 50 meters, 2 and 3 a range of 100 meters.

 

It seems that the first and last categories have the half range of all the
others ones. Is this correct? Shouldn't the range be the same for all
categories?

(same results with GRASS6.4, GRASS6.3 and GRASS6.2).

Many thanks in advance

 

A. Clerici

Parma University

Italy

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