Re: [osg-users] Grayscale texture
Hi Robert, My team have traced to using hardware generation of mipmaps as the reason why the compressed texture loads slower than uncompressed texture. We do not know the exact reason and have reproduced the same behaviour across NVIDIA and Intel-based GPU on both Linux and Windows system. Right now, we default to pre-build the mipmaps when we use OSGDEM and this gives us faster performance than uncompressed texture loading. Thank you! Cheers, Boon -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=58636#58636 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] Grayscale texture
H Boon, This is a driver/hardware specific issue rather than an OSG one. If you want to understand this then it would be best to approach the NVidia or Intel support forums. Robert. On 17 March 2014 02:22, Boon Wah boon...@gmail.com wrote: Hi, It appears that within texture.cpp in core OSG library, glTexImage2D is faster than glCompressedTexImage2D by about 80 - 100%. glTexImage2D is used when the texture data is uncompressed (e.g. RGB24) and glCompressedTexImage2D is used when the texture data is compressed (e.g. S3DXT1). I have time the execution on both Nvidia GPU and Intel HD4000 graphics. The timing difference is similar when using compressed and uncompressed. I have only profile this on Windows platform using the latest NVIDIA and Intel drivers. For NVIDIA driver, I have specifically enable full graphics performance using its control panel. In addition, I have tried to compile my texture with NVTT and it gives the same performance close to S3DXT1. I will like to understand on why compressed data takes longer to load onto GPU whereas uncompressed data performance is better. Will appreciate if somebody can enlighten me on this. Thanks in advance. Kind Regards, Boon Wah -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=58616#58616 ___ 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] Grayscale texture
Hi, It appears that within texture.cpp in core OSG library, glTexImage2D is faster than glCompressedTexImage2D by about 80 - 100%. glTexImage2D is used when the texture data is uncompressed (e.g. RGB24) and glCompressedTexImage2D is used when the texture data is compressed (e.g. S3DXT1). I have time the execution on both Nvidia GPU and Intel HD4000 graphics. The timing difference is similar when using compressed and uncompressed. I have only profile this on Windows platform using the latest NVIDIA and Intel drivers. For NVIDIA driver, I have specifically enable full graphics performance using its control panel. In addition, I have tried to compile my texture with NVTT and it gives the same performance close to S3DXT1. I will like to understand on why compressed data takes longer to load onto GPU whereas uncompressed data performance is better. Will appreciate if somebody can enlighten me on this. Thanks in advance. Kind Regards, Boon Wah -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=58616#58616 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] Grayscale texture
Hi Jimmy, Performance of various OpenGL calls is very dependent upon the driver and hardware you have, and in particular what formats they accelerate on the GPU varies, if you don't use the fast paths for that driver/hardware combination then you can see big performance drops as the operations are done on the CPU instead. What's specifically happening in your case I can't say, I know nothing about your specific usage, OS, hardware, drivers. Hopefully the above will give you some hints of where to look. Robert. On 5 November 2013 03:04, Boon Wah boon...@gmail.com wrote: Hi, I notice that glCompressedTexImage2D takes the longest time during texture loading. Can I understand what does this function actually does? I thought the texture decompression is handled by GPU, and loading to GPU actually should be significantly fast. In my testing, uncompress texture loads faster than compressed texture and this does not make sense to me. I will like to reduce the time in glCompressedTexImage2D as it ia significant in my application. Can somebody please advise me? Thanks. Kind Regards, Jimmy -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=57068#57068 ___ 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] Grayscale texture
Hi, I notice that glCompressedTexImage2D takes the longest time during texture loading. Can I understand what does this function actually does? I thought the texture decompression is handled by GPU, and loading to GPU actually should be significantly fast. In my testing, uncompress texture loads faster than compressed texture and this does not make sense to me. I will like to reduce the time in glCompressedTexImage2D as it ia significant in my application. Can somebody please advise me? Thanks. Kind Regards, Jimmy -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=57068#57068 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] Grayscale texture
Hi, I tried --compression flag and --compression-dxt1 flag in OSGDEM. However, when I step through OSG when I view the IVE, I noticed that the texture compression all defaults to SCTC-DX1. The size of the compiled textures are the same. Can anybody advise on how to select the ARB extension as suggested. Kind Regards, Jimmy -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=56865#56865 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] Grayscale texture
Hi Jimmy, I don't recall the options or whether compressed greyscale is possible with VPB/osgdem as it's a while since I worked on the code. What may be the best thing to do is simple disable compression, the option is probably ---no-compression. Robert. On 18 October 2013 14:59, Boon Wah boon...@gmail.com wrote: Hi, I tried --compression flag and --compression-dxt1 flag in OSGDEM. However, when I step through OSG when I view the IVE, I noticed that the texture compression all defaults to SCTC-DX1. The size of the compiled textures are the same. Can anybody advise on how to select the ARB extension as suggested. Kind Regards, Jimmy -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=56865#56865 ___ 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] Grayscale texture
jimmy82 wrote: Hi, Is there any way that I can choose a suitable texture format that represents only 8-bit gray-scale texture? So far, I understand that the internal representation of gray-scale and coloured texture are similar under OpenGL compression schemes and S3TC. All S3TC compressions use at least 3 color channels. You need to use RGTC1 compression for 8-bit one channel texture ( from this OpenGL extension : ARB_texture_compression_rgtc ). Fortunatelly OSG handles that compression. You can use nvcompress application from Nvidia Texture Tools to compress your images ( this is bc4 compression, I think ). Paweł Księżopolski -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=56831#56831 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
[osg-users] Grayscale texture
Hi, I am compiling a large satellite imaginary using OSGDEM. As I want to reduce the size of the texture to a minimum, I worked only with gray-scale 8-bit satellite imaginary. Is there any way that I can choose a suitable texture format that represents only 8-bit gray-scale texture? So far, I understand that the internal representation of gray-scale and coloured texture are similar under OpenGL compression schemes and S3TC. Any help will be appreciated. Thanks. Kind Regards, Jimmy -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=56818#56818 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
