Hi,
On 15/07/2011 11:14, Diana Kittelmann wrote:
Hi,
I'm implementing a lidar scanner simulator ins osg and got kind oft
stucked.
I'm loading a world from file as my scene and let my sensor fly
through the world, everything works fine. From a 3d Party I got a
Vertex- and Fragment Shader to calculate the actual view of the lidar
scanner.
In other words what I get right now is an image with colored Pixel
-the color of a pixel tells me the distance between the sensor and
point of object hit by the laser ray -the image doesent have any
depth informations -when I get the distance-values I have to send
them vie ethernet (not relevant here cause already implemennted) so
waht I need as result ist a vector of long-values including the
length of the laser rays
And now I don't know how I can get the distance or better I don't
know how I can get the RGB-Values of the Pixel in the image. (notice
that image doesen't mean I get an Image-object but the actual picture
shown in the View)
I tried to realize it via osg::Image:
Code:
osg::Image* buffer = new osg::Image;
...
void getBuffer() { buffer->readPixels(0,0,200,200,GL_RGB,GL_FLOAT);
float* bufferRaw; bufferRaw = (float*) buffer->data();
... }
you have the right idea with readpixels, but you must make sure that the
readpixels is happening after the camera has drawn so that the context
where the data lives is still active. Stick it into a drawcallback. See
the osgscreencapture example for inspiration. It also shows the other
methods of reading data back to the CPU.
With this I just get a wrong value (something undefined like
-4.3160208e+008)
I have no idea if I am on the right way or totally wrong. I'm just
new to OSG. So can anyone give me a tip what I should try or for what
to search ...
I'm using OSG 2.8.1, have one View and one Camera (the one the view
got by default) and I'm using a kind of complex class hierarchie (ie:
I have a cameraView-clas which realizes the view, and I have a
lidarView-class which realizes the lidar stuff and calls the shaders
and which inherits from the cameraView).
Thank you!
Cheers, Diana
PS: The worst ist that it hast to be very fast. I have to write a
real-time lidar scanner simulation.[/code]
You'll probably be limited by the amount of data you can read back from
the GPU to CPU. You'll have to test this on your setup and you can work
out the required rate you'll need.
jp
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