[Shapelib] Multipatch creation error

[Oscar Gomez Mateu]

Hi again,

some extended information in the multipatch problem. The rendering problems
(and interpretation of the multipatches as PolygonZM features) do only occur
if there is a polygon with an inner hole (which is the case of the polygon 0
in the previously attached files).

I hope this helps
Oscar

2010/9/16 Oscar Gomez Mateu <gomezmateu.oscar at gmail.com>

> Hi,
>
> coming back on the Multipatch creation problem.
>
> I created an application that takes 2D polygon shapes (attached
> 'simpleshape2.shp') and creates a 3D polygon shape imitating an extrusion.
> Every original polygon turns into a bottom polygon (at 0 height), top
> polygon (at RELELEV attribute height) and as many verticall walls as vertex
> has the original polygon. An example can be seen in the attached
> 'simpleshape2_extr.shp'. In ArcGIS I merge all the polygons with the same ID
> into a multipatch with the tool 'Layer 3D to Feature Class' and I get the
> attached 'simpleshape2_extr_merge.shp'.
>
> I then modified my application to create a multipatch shape as similar as
> possible to the merged example. The result is the attached
> 'simpleshape2M_extr.shp'.
>
> Doing a shapedump of the 2 end result shapes it is possible to see that
> they are (beside the M values) identical. But 'simpleshape2_extr_merge.shp'
> gets rendered in ArcScene and the features are considered 'MultipatchM' and
> 'simpleshape2M_extr.shp' is not rendered and the features are considered
> PolygonZM.
>
> Any idea what could be wrong?
>
> Thanks
> Oscar
>
> 2010/9/14 Frank Warmerdam <warmerdam at pobox.com>
>
>
>> > Oscar Gomez Mateu wrote:
>> >> I am having problems with the Multipatch creation. As an example, I
>> >> create a Multipatch composed of 2 triangles in a TriangleFan (a
>> >> horizontal square -4points-) and a Ring (a vertical square sharing on
>> of
>> >> the triangles lines -5 points-).
>>
>>
>> Oscar,
>>
>> The shpdump for your file, created with the shpdump utility distributed
>> as part of shapelib looks like this:
>>
>> warmerda at gdal64[109]% shpdump testmultipatch.shp
>> Shapefile Type: PolygonZ   # of Shapes: 1
>>
>> File Bounds: (       0.000,       0.000,0,5)
>>          to  (      10.000,      10.000,10,5)
>>
>> Shape:0 (MultiPatch)  nVertices=9, nParts=2
>>   Bounds:(       0.000,       0.000, 0)
>>       to (      10.000,      10.000, 10)
>>      (       0.000,       0.000, 10) TriangleFan
>>      (      10.000,       0.000, 10)
>>      (      10.000,      10.000, 10)
>>      (       0.000,      10.000, 10)
>>    + (       0.000,       0.000, 10) Ring
>>      (       0.000,      10.000, 10)
>>      (       0.000,      10.000, 0)
>>      (       0.000,       0.000, 0)
>>      (       0.000,       0.000, 10)
>>
>> I have not done a complete analysis but it looks roughly plausible.
>>
>> I can't comment on why this would not display properly in ArcScene.
>>
>> Best regards,
>> --
>>
>> ---------------------------------------+--------------------------------------
>> I set the clouds in motion - turn up   | Frank Warmerdam,
>> warmerdam at pobox.com
>> light and sound - activate the windows | http://pobox.com/~warmerdam<http://pobox.com/%7Ewarmerdam>
>> and watch the world go round - Rush    | Geospatial Programmer for Rent
>>
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>
>
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