Hi,
I have created a point vector from a coastline using v.to.points:
v.to.points input=CanCoast_Shoreline type=line output=CanCoast_Shoreline_points use=vertex --v
This works fine, and the next thing I want to do is upload raster slope values from a DEM to the attribute table of the points vector using v.what.rast, but I get tons of warnings like these:
WARNING: Multiple points (12) of category 16, value set to ‘NULL’
I assume this is telling me the points have duplicate categories?
So to get around this, I tried recreating the points, this time without an attribute table, using v.to.points -t, then adding the table and categories manually:
v.to.points input=CanCoast_Shoreline type=line output=CanCoast_Shoreline_points use=vertex -t --v --o
v.db.addtable map=CanCoast_Shoreline_points columns=“Slope_percent integer”
v.category input=CanCoast_Shoreline_points option=add output=CanCoast_Shoreline_points_with_cat
But running v.what.rast still gives me the same error as before.
I ran v.categories in report mode to see what is going on:
v.category input=CanCoast_Shoreline_points_with_cat option=report
Layer/table: 1/CanCoast_Shoreline_points_with_cat
type count min max
point 105427 1 1692
line 0 0 0
boundary 0 0 0
centroid 0 0 0
area 0 0 0
face 0 0 0
kernel 0 0 0
all 105427 1 1692
Layer: 2
type count min max
point 105427 1 105427
line 0 0 0
boundary 0 0 0
centroid 0 0 0
area 0 0 0
face 0 0 0
kernel 0 0 0
all 105427 1 105427
Where did the two layers come from? I thought v.to.points -t wasn’t supposed to make an attribute table. And the fact that the ‘max’ value reported above is ‘1692’ seems to be a hangover from the line features they were created from.
In this case, I don’t care about the IDs or categories of the lines the points originated from; I want unique categories for the 105427 points that were made so I can then successfully run v.what.rast and upload my DEM slope values.
It’s been a while since I’ve used these tools, so I’m a little rusty. Is there a way to do this?
~ Eric.