[GRASS-user] v.to.points doesn't create a point layer?

GRASS GRASS user
1

Hi,
I was using v.what.rast and I got an error that no point layer was found.
the layer that was passed was created using v.to.points from a vector file.

The v.to.points creates two tables in SQLite and I didn’t like it. I exported it to a geo package format and then imported it as the point layer I wanted to see.(is there another way, please let me know)

I tried v.what.rast and I experienced the same error that a point layer can’t be found on both point layers.This is the v.what.rast command that generates an error:

v.what.rast --verbose map=POM@Mehrdad raster=ABC@Mehrdad column=ABC

The error is:

Reading features from vector map…
No features of type (point) found in vector map POM@Mehrdad

questions:

  • Do you know a way that v.to.points creates only one table in SQLite?
  • Why I get the error in v.what.rast? I have looked at the POM and it is really a points layer (it appears like that in GRASS)

Thanks for your help,

Mehrdad

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Mehrdad Varedi

2
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On 10/21/18 7:37 AM, Mehrdad Varedi wrote:

Hi,
I was using v.what.rast and I got an error that no point layer was found.
the layer that was passed was created using v.to.points from a vector file.

The v.to.points creates two tables in SQLite and I didn’t like it. I exported it to a geo package format and then imported it as the point layer I wanted to see.(is there another way, please let me know)

What was the input to v.to.points? The two tables in sqlite result from the way that v.to.points works: it creates 2 “layers” attached to the output points vector: layer 1 with the categories of the original lines (or boundaries) and layer 2 with new individual categories for each point.

So when you go to the next step, v.what.rast, you probably want to specify “layer=2”

I tried v.what.rast and I experienced the same error that a point layer can’t be found on both point layers.This is the v.what.rast command that generates an error:

v.what.rast --verbose map=POM@Mehrdad raster=ABC@Mehrdad column=ABC

The error is:

Reading features from vector map…
No features of type (point) found in vector map POM@Mehrdad

questions:

  • Do you know a way that v.to.points creates only one table in SQLite?
  • Why I get the error in v.what.rast? I have looked at the POM and it is really a points layer (it appears like that in GRASS)

First guess: have you set the computational region to the ABC raster?? (FAQ # 0 in GRASS)

Please post the outputs from:

g.region -p

r.info ABC

v.info POM

Thanks for your help,

Mehrdad

–

Mehrdad Varedi

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-- 
Micha Silver
Ben Gurion Univ.
Sde Boker, Remote Sensing Lab
cell: +972-523-665918
3

Great! Thank you Micha,
I had reset the region and forgot to set it properly. Thanks for your help.

The team here are all amazing! Good work and I hope someday I could compensate so much support :slight_smile:

M.

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Mehrdad Varedi