Re: [osg-users] Mipmapping for downsampling
Hi Sebastian, Ok, I've displayed the different mipmap in my application and I realized that a black square is propagated along the different mipmap level (see pictures). Finally the last level became completely black. We solved the problem by changing the model involved. Thanks for the precious advices, Kenzo -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=50346#50346 Attachments: http://forum.openscenegraph.org//files/mipmap7_205.png ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] Mipmapping for downsampling
Hi looks like you was hitting NaN's somewhere, as they propagate in such fashion. Cheers. 28.09.2012, 18:11, Kenzo Lespagnol kenzo.lespag...@cm-labs.com: Hi Sebastian, Ok, I've displayed the different mipmap in my application and I realized that a black square is propagated along the different mipmap level (see pictures). Finally the last level became completely black. We solved the problem by changing the model involved. Thanks for the precious advices, Kenzo -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=50346#50346 Attachments: http://forum.openscenegraph.org//files/mipmap7_205.png ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] Mipmapping for downsampling
Okay, one last try: 1. Have you tried showing the last mip-level (i.e. avg. lum) in a separate window so you can check the value? 2. Have you double checked your actual tone-mapping? (say by providing the average luminance via uniform)? I'm asking this rather silly questions, because last time I looked for an error I simply assumed the error to be in a step where indeed it was not ;-) cheers Sebastian Thank you Sebastian for your support. I appreciate it. More or less. I don't know the exact wording from the specification, but the mipmapping should actually do a bilinear interpolation for 4 neighbouring texels per mip level. I've found many examples that used the last LOD for average lum. This is what I expecting from the mipmapping to implement my tone mapping algorithm. That looks okay. I suppose you are using FrameBuffer Objects and this the setup code for the texture. Exactly, I'm using FBO to render-to-texture. Code: mainCamera-setRenderTargetImplementation(osg::Camera::FRAME_BUFFER_OBJECT, osg::Camera::PIXEL_BUFFER_RTT); Have you simply tried the 1000.0 (it is clamped to the last level)? Yes I've tried it. But still the issue. Can you maybe provide a screenshot of your artifacts? Actually a screenshot will not help you as there is no really artifact. Basically the screen is flashing. Some particularly views give a brighter image as no tone mapping was disable. At this moment if I move just a bit the image come back darker as expected from my tone mapping. It's little bit weird... I'm wondering if it is actually the mipmapping or if it is conflicting with an other stuff. Thanks a lot, Kenzo -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=50322#50322 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] Mipmapping for downsampling
Hi Kenzo. I think you are misinterpreting the last argument to the textureLod, which is an offset IIRC. I use the following to sample the last level (which is 1 px and gives you exactly the average): exp(texture2DLod(LuminanceSampler, vec2(0.5,0.5), 1000.0)); cheers Sebastian Hi, I've managed to generate my mipmap via the hardware. But I'm guessing I don't have the good mipmap as the result of my tone mapping is unstable. The screen is brighter in a jerky manner for some position of the camera. As below, how to create my mipmap: Code: osg::ref_ptrosg::Texture2D tex2D = dynamic_castosg::Texture2D*(logAveragedLumTexture.get()); tex2D-setNumMipmapLevels(9); tex2D-setFilter(osg::Texture::MAG_FILTER, osg::Texture::LINEAR); tex2D-setFilter(osg::Texture::MIN_FILTER, osg::Texture::LINEAR_MIPMAP_LINEAR); Then I'm retrieving the values of the smallest mipmap (2x2), by accessing to the LOD level 9 as my texture is 512 by 512 as the beginning: Code: // get last mipmap level as 2x2 texture vec4 lastMipmapLevel; lastMipmapLevel.x = textureLod(logAveragedLumTexture, vec2(0.25, 0.25), 9.0).r; lastMipmapLevel.y = textureLod(logAveragedLumTexture, vec2(0.75, 0.25), 9.0).r; lastMipmapLevel.z = textureLod(logAveragedLumTexture, vec2(0.25, 0.75), 9.0).r; lastMipmapLevel.w = textureLod(logAveragedLumTexture, vec2(0.75, 0.75), 9.0).r; I'm not sure about the way to access to my mipmap. I've tried other texture coordinates but the results is still unstable. -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=50295#50295 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] Mipmapping for downsampling
Hi Sebastian, I've followed your advice, but I've still the issue. So it's seems I'm using a wrong way to generate my mipmaps. Is hardware mipmap generation actually average the values between the different mipmap levels? Code: logAveragedLumTexture-setUseHardwareMipMapGeneration(true); logAveragedLumTexture-allocateMipmapLevels(); osg::ref_ptrosg::Texture2D tex2D = dynamic_castosg::Texture2D*(logAveragedLumTexture.get()); tex2D-setNumMipmapLevels(numMipMap); tex2D-setFilter(osg::Texture::MIN_FILTER, osg::Texture::LINEAR_MIPMAP_NEAREST); About the last parameter, I've checked the OpenGL specifications and I'm understanding that the last parameter will correspond to the lod level if no bias is given. See section 8.14.1, formula (8.4), (8.5) and (8.6). Thank you! Kenzo -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=50315#50315 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] Mipmapping for downsampling
Am 26.09.2012 17:27, schrieb Kenzo Lespagnol: Hi Sebastian, I've followed your advice, but I've still the issue. So it's seems I'm using a wrong way to generate my mipmaps. Is hardware mipmap generation actually average the values between the different mipmap levels? More or less. I don't know the exact wording from the specification, but the mipmapping should actually do a bilinear interpolation for 4 neighbouring texels per mip level. I've found many examples that used the last LOD for average lum. Code: logAveragedLumTexture-setUseHardwareMipMapGeneration(true); logAveragedLumTexture-allocateMipmapLevels(); osg::ref_ptrosg::Texture2D tex2D = dynamic_castosg::Texture2D*(logAveragedLumTexture.get()); tex2D-setNumMipmapLevels(numMipMap); tex2D-setFilter(osg::Texture::MIN_FILTER, osg::Texture::LINEAR_MIPMAP_NEAREST); That looks okay. I suppose you are using FrameBuffer Objects and this the setup code for the texture. About the last parameter, I've checked the OpenGL specifications and I'm understanding that the last parameter will correspond to the lod level if no bias is given. See section 8.14.1, formula (8.4), (8.5) and (8.6). Okay, but the last mip levels number is dependent on the texture resolution. Have you simply tried the 1000.0 (it is clamped to the last level)? Also: as you put the log of the luminance into the texture, you must uncompress it afterwards (i.e. pow) to get the average in linear space. Can you maybe provide a screenshot of your artifacts? Thank you! Kenzo -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=50315#50315 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] Mipmapping for downsampling
Thank you Sebastian for your support. I appreciate it. More or less. I don't know the exact wording from the specification, but the mipmapping should actually do a bilinear interpolation for 4 neighbouring texels per mip level. I've found many examples that used the last LOD for average lum. This is what I expecting from the mipmapping to implement my tone mapping algorithm. That looks okay. I suppose you are using FrameBuffer Objects and this the setup code for the texture. Exactly, I'm using FBO to render-to-texture. Code: mainCamera-setRenderTargetImplementation(osg::Camera::FRAME_BUFFER_OBJECT, osg::Camera::PIXEL_BUFFER_RTT); Have you simply tried the 1000.0 (it is clamped to the last level)? Yes I've tried it. But still the issue. Can you maybe provide a screenshot of your artifacts? Actually a screenshot will not help you as there is no really artifact. Basically the screen is flashing. Some particularly views give a brighter image as no tone mapping was disable. At this moment if I move just a bit the image come back darker as expected from my tone mapping. It's little bit weird... I'm wondering if it is actually the mipmapping or if it is conflicting with an other stuff. Thanks a lot, Kenzo -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=50322#50322 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
[osg-users] Mipmapping for downsampling
Hi, I'm currently implementing my own global tone mapping (without osgPPU). As a first iteration, I'm averaging the luminance by using hardware mipmap generation. Then I'm wondering if there is a mean to retrieve the last level of mipmapping from a osg::Texture? Is someone have a useful link I missed during my searchs? A example will be also appreciated. Thank you! Cheers, Kenzo -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=50237#50237 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] Mipmapping for downsampling
Hi, I've managed to generate my mipmap via the hardware. But I'm guessing I don't have the good mipmap as the result of my tone mapping is unstable. The screen is brighter in a jerky manner for some position of the camera. As below, how to create my mipmap: Code: osg::ref_ptrosg::Texture2D tex2D = dynamic_castosg::Texture2D*(logAveragedLumTexture.get()); tex2D-setNumMipmapLevels(9); tex2D-setFilter(osg::Texture::MAG_FILTER, osg::Texture::LINEAR); tex2D-setFilter(osg::Texture::MIN_FILTER, osg::Texture::LINEAR_MIPMAP_LINEAR); Then I'm retrieving the values of the smallest mipmap (2x2), by accessing to the LOD level 9 as my texture is 512 by 512 as the beginning: Code: // get last mipmap level as 2x2 texture vec4 lastMipmapLevel; lastMipmapLevel.x = textureLod(logAveragedLumTexture, vec2(0.25, 0.25), 9.0).r; lastMipmapLevel.y = textureLod(logAveragedLumTexture, vec2(0.75, 0.25), 9.0).r; lastMipmapLevel.z = textureLod(logAveragedLumTexture, vec2(0.25, 0.75), 9.0).r; lastMipmapLevel.w = textureLod(logAveragedLumTexture, vec2(0.75, 0.75), 9.0).r; I'm not sure about the way to access to my mipmap. I've tried other texture coordinates but the results is still unstable. -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=50295#50295 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
