[GRASS-user] v.class.mlR Error

[Moritz Lennert]

On 19/06/18 19:32, Jamille Haarloo wrote:
> Hi Moritz,
> 
> Thanx for the advice! Will check it out. From the publications I read, I 
> inferred it was better to use an alternative method (data mining/ 
> object-based) on high resolution imagery than pixel-based.

Generally this is true, but when you work in landscapes which don't 
really have sharp edges, this can sometimes be counterproductive. There 
is not clear scientific answer, though, and you just have to try what 
works best.

> I also read 
> that texture metrics (e.g. standard deviation of spectral bands) may 
> capture the unique “patterns” of wetlands and other ecosystems (given 
> the appropriate spatial scale). Will continue testing and checking for 
> improvements.

I think in this case "real" texture measurements (e.g. those provide by 
r.texture, might even be more efficient than just the standard 
deviations of bands. Again, you will have to do a bit of trial and error 
to determine which texture measure works best.

> 
> I was running directy from GRASS GIS, but recently created and used a 
> new training map with the lower case column name. My apologies for the 
> inconsistency, but good to know that the previous training map wasn't 
> the issue.


Actually I noticed that your error message concerned the qbwwv voting 
algorithm which wasn't in the command line you provided. I was just able 
to reproduce your error using that same voting scheme. I'll have to dig 
into this a bit deeper to see where the error comes from.

Moritz