[Paraview] Offset between grid and points on spherical projection

Fri Jun 27 15:24:23 EDT 2014

Gotcha, thank you.

-fernando

On Fri, Jun 27, 2014 at 12:01 PM, Burlen Loring <burlen.loring at gmail.com>
wrote:

>  btw, the default is to automatically disable specular affects when
> pseudocoloring. If you want specular affects in pseudocolor plots you can
> enable it in the settings menu. edit->settings->general. The fact that it's
> automaticly changed on us is a bit confusing. I guess the rational is that
> specular highlights modify the coloring, the down side of course is that
> your depth preceptipon of curved surface reduced and then also as you
> noticed that it looks funny when you have other surfaces that are not
> pseduocolored.
>
> On 6/26/2014 4:25 PM, Fernando Paolo wrote:
>
> Indeed, turning off specular highlights on the sphere produces the same
> lightning on both surfaces (the sphere was set to 0.2 and the grid to 0.1).
>
>  Thanks for your help, Ken!
> -fernando
>
>
>
>
> On Thu, Jun 26, 2014 at 2:05 PM, Moreland, Kenneth <kmorel at sandia.gov>
> wrote:
>
>>   I don't know why the lighting is different, but here some guesses you
>> can try.
>>
>>  The default resolution for the sphere is quite coarse and results in
>> large facets. The lighting on the large flat facets of the sphere might be
>> quite different than the smaller facets of the grid. Try increasing the
>> resolution of the sphere.
>>
>>  The sphere source comes with normals on the points whereas your grid
>> might not. That could result in different lighting equations. You could try
>> running the generate surface normals on your grid (assuming it is poly
>> data). That's assuming that your grid is not a clipped sphere, which could
>> result in inconsistent normals as the edge.
>>
>>  It could be that the sphere is using specular highlighting whereas the
>> colored mesh is not. Try turning off specular highlighting on the sphere
>> (under the display properties).
>>
>>  -Ken
>>
>>   From: Fernando Paolo <fspaolo at gmail.com>
>> Date: Thursday, June 26, 2014 2:29 PM
>> To: Kenneth Moreland <kmorel at sandia.gov>
>> Cc: "paraview at paraview.org" <paraview at paraview.org>
>> Subject: [EXTERNAL] Re: [Paraview] Offset between grid and points on
>> spherical projection
>>
>>   Ok, that seems to work for the points. Thanks so much, Ken.
>>
>>  Not sure if this is also related to a similar issue. But when I add a
>> 'Source -> Sphere' of radius = 1 (same radius as the grid) to the plot,
>> there is different "illumination" between the surface of the sphere and the
>> grid. This "effect" also changes with angle of view. In the attached figure
>> you can clearly see how the illumination changes across the boundary
>> between the surface of the sphere (lighter) and the grid (darker). This two
>> surfaces should blend.
>>
>>  Once again, thank you!
>> -fernando
>>
>>
>>  [image: Inline image 1]
>>
>>
>>
>> On Thu, Jun 26, 2014 at 12:45 PM, Moreland, Kenneth <kmorel at sandia.gov>
>> wrote:
>>
>>>   This looks like it might be caused by the coincident topology
>>> resolution feature in ParaView's rendering. The problem when trying to draw
>>> surfaces and points or lines on that surface as you are doing is that you
>>> get z-buffer fighting so that the points/lines don't just show up on top
>>> like you want.
>>>
>>>  ParaView implements a couple of tricks to prevent this from happening,
>>> but they all sometimes cause shifts in the data so that they do not line up
>>> correctly. My suggestion is to first turn off coincident topology
>>> resolution and see if that fixes this problem (although it might introduce
>>> a new one). Go to settings and then Render View -> General to get to the
>>> coincident topology resolution options.
>>>
>>>  -Ken
>>>
>>>   From: Fernando Paolo <fspaolo at gmail.com>
>>> Date: Thursday, June 26, 2014 1:36 PM
>>> To: "paraview at paraview.org" <paraview at paraview.org>
>>> Subject: [EXTERNAL] [Paraview] Offset between grid and points on
>>> spherical projection
>>>
>>>   Hello,
>>>
>>>  I have a 2d grid projected on top of a spherical surface. On the same
>>> surface, and on top of the grid, I am also projecting a set of points
>>> delimiting the boundaries of the quantity in question. The problem is that
>>> both the grid and the points when plotted together are displayed with an
>>> offset in between them (in the "r" direction from the spherical
>>> projection). Also interesting is the fact that when I change the angle of
>>> view the "offset" also changes (*see attached figures*).
>>>
>>>  The coordinates of both the grid and the points are simply converted
>>> from spherical lon/lat/radius=1 to cartesian xyz.
>>>
>>>  The points are projected using an UNSTRUCTURED GRID format (polydata
>>> ascii file). And the grid is projected using the XDMF 3DSMesh, with the
>>> following template:
>>>
>>>     <Grid Name="Mesh" GridType="Uniform">
>>>      <Time Value="%f" />
>>>      <Topology TopologyType="3DSMesh" NumberOfElements="{0} {1} {2}"/>
>>>      <Geometry GeometryType="XYZ">
>>>        <DataItem Name="Coordinates" Dimensions="{3} {4}"
>>> NumberType="Float" Precision="4" Format="HDF">
>>>          PATH_TO_XYZ
>>>        </DataItem>
>>>      </Geometry>
>>>
>>>      <Attribute Name="DATA_NAME" AttributeType="Scalar" Center="Cell">
>>>        <DataItem Dimensions="{5} {6} {7}" NumberType="Float"
>>> Precision="4" Format="HDF">
>>>          PATH_TO_DATA
>>>        </DataItem>
>>>      </Attribute>
>>>    </Grid>
>>>
>>>  If both datasets have a radius = 1, why is there any offset in between
>>> them? Since this offset also changes with the angle of view, it seems that
>>> both datasets are not being projected on top of the same spherical surface
>>> (note: I've tried setting different radius for both datasets). How can I
>>> fix this?
>>>
>>>  I appreciate any help!
>>> -fernando
>>>
>>>
>>>  [image: Inline image 1]
>>>
>>>  [image: Inline image 2]
>>>
>>>
>>>  --
>>> Fernando Paolo
>>> Institute of Geophysics & Planetary Physics
>>> Scripps Institution of Oceanography
>>> University of California, San Diego
>>>
>>> web: fspaolo.net
>>>
>>
>>
>>
>>  --
>> Fernando Paolo
>> Institute of Geophysics & Planetary Physics
>> Scripps Institution of Oceanography
>> University of California, San Diego
>>
>> web: fspaolo.net
>>
>
>
>
>  --
> Fernando Paolo
> Institute of Geophysics & Planetary Physics
> Scripps Institution of Oceanography
> University of California, San Diego
>
> web: fspaolo.net
>
>
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-- 
Fernando Paolo
Institute of Geophysics & Planetary Physics
Scripps Institution of Oceanography
University of California, San Diego

web: fspaolo.net
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