Hi Ken,
For that figure you mention I turned on "surface with edges" to show the
cell size better. Sorry I can see how that could be confusing. But just
to clarify, there aren't actually any holes in the surface.
Here is another zoom in of the same area where "surface with edges" is
off and you can see that there are no holes.
http://nashi-submaster.ucsd.edu/movies/PV/bug-zoom.png
Now I also have hit a case where after running through D3 I got a hole
at the process boundary. this run had 80 processes, the surface shown
has dimensions of 5.5 x 10 units with 1500 x 2727quads with side 0.0036
units.
http://nashi-submaster.ucsd.edu/movies/PV/bug-d3.png
I am only seeing this with the small quads and in parallel at process
boundaries.
Burlen
Moreland, Kenneth wrote:
Burlen,
For the zoom in, you say there are no holes/lines, but in the image I
see a grid of lines. It looks like you have a bunch of little quads
with spacing in between them. Is this the case? If so, then the “hole”
artifacts you see on the bottom of the screen are probably simply
aliasing artifacts. They are places where the pixel happens to align
right where the gap is.
I can’t think of an easy way around this (other than to modify your
data to remove the gaps, if that makes sense). Anti-aliasing
techniques such as oversampling or smoothing would probably fix the
problem, but they would also break the parallel rendering so they are
no good.
-Ken
On 12/5/09 12:18 AM, "burlen" <[email protected]> wrote:
its ugly but I get a lot better performance by splitting the work up
dynamically with a small grain size. in the run shown below there are
only 16 processes but there are a whole lot of process boundaries.
I was able to reproduce it on a second system today.
these holes are pretty non-deterministic in where they show up. moving
the camera they can show up in different places. Which makes sense if
this is related to some parallel rendering/finite precision issue with
all those process boundaries. The small size of the quads are also a
factor, because I didn't ever notice it before when using larger
quads.
I saved the data as a legacy file and opening it on my desktop
there are
no issues, so its definitely a parallel only issue. Also running
through
D3 seems to fix it, but the issue may still be there because with the
minimal number of process boundaries its much less likely to get the
camera in just the right position.
Berk Geveci wrote:
> Ouch. That's very distributed :-) Does the problem go away when you
> decrease the number of partitions?
>
> On Thu, Dec 3, 2009 at 10:55 AM, burlen <[email protected]>
wrote:
>
>> I'm seeing lines where the background shows through a surface
polydata of
>> quads. When I zoom into the region to investigate the holes are
gone. Moving
>> the image around the holes appear in different places. They
depend on camera
>> position. In this surface there are 2.5E6 quads. the area is
10x16 units and
>> the number of quads is 1250x2000. each quad has 0.008 units on a
side. I
>> hadn't seen the holes before going to this higher resolution.
It's likely
>> that the hole is near a process boundary, in my polydata filter
each process
>> adds his quads to his output polydata, in this run the quads are
distributed
>> in strips of 512 as needed.
>>
>> 3 holes/lines in bottom half of the image (black background
shows through):
>> http://nashi-submaster.ucsd.edu/movies/PV/bug.png
>>
>> zoom in no holes/lines:
>> http://nashi-submaster.ucsd.edu/movies/PV/bug-zoom-2.png
>>
>> process boundaries (from process id filter):
>> http://nashi-submaster.ucsd.edu/movies/PV/bug-procs.png
>>
>> Should PV be able to handle a polydata distributed like this?
>>
>>
>>
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**** Kenneth Moreland
*** Sandia National Laboratories
***********
*** *** *** email: [email protected]
** *** ** phone: (505) 844-8919
*** web: http://www.cs.unm.edu/~kmorel <http://www.cs.unm.edu/%7Ekmorel>
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