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.

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

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.

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

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

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

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

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

[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