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Question

Surface Modeller "minimum number of points"

  • February 25, 2019
  • 2 replies
  • 83 views
R

I want to create a DEM from Multipatch-geometry contained in a geodatabase, for doing that I thought using the surface modeller could work, where in surface modeller I group the points by the UUID generated attribute:

0684Q00000ArElBQAV.png

But the errors are

"The specified cell size of '2' units in the y axis is invalid. Cell size must be less than raster extents"
"Surface Model cannot be constructed. Either all points are linear or initial set of points did not consist of 3 non NAN elevations"

For the first error I think it's due to objects with 3 points in less than a diameter of 2 meters

Second error is due to objects with less than 3 points

Questions: 

1) how could I exclude/drop/ignore geometries with less than 3 points ?

2)how could I still add a cell value to objects less than 2 m ?

2 replies

gio
Contributor
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  • gioContributor
  • Contributor
  • February 25, 2019

@raphaelvallat11

If you group the points by a unique identifier then you are actually trying to build surfaces with a single point. (each is a group of 1)

(Unless they were aggregates prior to assigning a UI.)

 

Of course this causes the second error message, as unit 2 is larger then 0.

 

You need to check why you are Grouping in the Surface Modeller. As far as I can see there is no reason for it in your example, as you seem to be grouping objects to single object groups.

 

R
gio wrote:

@raphaelvallat11

If you group the points by a unique identifier then you are actually trying to build surfaces with a single point. (each is a group of 1)

(Unless they were aggregates prior to assigning a UI.)

 

Of course this causes the second error message, as unit 2 is larger then 0.

 

You need to check why you are Grouping in the Surface Modeller. As far as I can see there is no reason for it in your example, as you seem to be grouping objects to single object groups.

 

@gio Thank you. The geometry of the input is multipatch, I m not familiar with it and may not be understanding it correctly. I think but I'm not sure that every multipatch feature has a unique ID (in my case every building), and all points (vertices) of each feature are grouped by one ID in the UUID generator. I tried without the UUID generator, and the problem is that it does interpolate a DEM in between buldings, where I actually want NoData. And one raster per building, which I would later merge in a mosaicker. Any thoughts on my reasoning ? or it could work

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