Hi
Josiah
Am 22.07.2016 um 13:00 schrieb Josiah Jideani:
Hi,
I am developing a scientific visualization application using Qt and
Openscenegraph. I am trying to create a 3D osg::Image to add to an osgVolume.
I am having problems allocating the image data when I call the allocateImage
member function (see the code snippet below).
The allocation works for equal dimensions less than 640.
When I try to allocate anything above 640x640x640 but less than 800x800x800, it
seems to allocate successfully because image_s, image_t and image_r hold the
correct sizes however when I try to write to the image data (the nested for
loops) a segmentation fault is thrown at data[0] = 0.0f when s = 0; t = 0; and
r = some random but valid number.
Putting the numbers together, 640^3 with 4*4 bytes (float and rgba) hits
the 4 gig limit.
I believe the image size used internally by OSG is an unsigned int(which
on most platforms is 32bits) , so that is probably what you're
hitting.[1] Could you check what the calculated image size returns, when
you encounter the allocation fails?
Typ
If my theory is right, we would have to change the data type used for
calculation to long/size_t. (Seems like the calculation and the
constructor are the only places that fail to use the correct size)
Cheers
Sebastian
[1]
http://trac.openscenegraph.org/projects/osg//browser/OpenSceneGraph/trunk/src/osg/Image.cpp?rev=10890
*unsigned* *int* *Image::getTotalSizeInBytesIncludingMipmaps*() *const
*
I can allocate and write to the image data with sizes between 800x800x800 and
1024x1024x1024, but a segmentation fault is thrown from the object code after
the call to the viewer's frame() method.
And finally for sizes above 1024 the allocation completely fails as image_s
image_t and image_r all hold 0.
Any clue on how to solve this? It was my understanding that the maximum size of
the image is limited by the maximum 3D texture size of the graphics card which
for the Quadro K4200 that I'm using is 4096x4096x4096. So why am I only able
to allocate a 640x640x640 image?
These are the specifications of my system:
Operating system: Opensuse Leap 42.1
RAM: 128GB
Graphics Card: Quadro K4200
Qt: Qt 4.7.1
OSG version: 3.2.3
Are you trying to compensate something? ;-)
Thank you!
Cheers,
Josiah
Code:
osg::ref_ptr<osg::Image> image = new osg::Image
image->allocateImage(1024, 1024, 1024, GL_RGBA, GL_FLOAT);
int image_s = image->s();
int image_t = image->t();
int image_r = image->r();
for(int s = 0; s < image_s; s++)
{
for(int t = 0; t < image_t; t++)
{
for(int r = 0; r < image_r; r++)
{
float* data = (float*) image->data(s,t,r);
data[0] = 0.0f;
data[1] = 0.0f;
data[2] = 1.0f;
data[3] = 0.1f;
}
}
}
------------------
Read this topic online here:
http://forum.openscenegraph.org/viewtopic.php?p=68195#68195
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