What is the advantage of using DDS textures?

Article Details



Poster: Morten
Article ID: 691
Posted: Thu 04 Feb 2016
Approved: Yes

QUESTION
What is the advantage of using DDS textures?

ANSWER
The advantage of using DDS textures for your materials is that this file type makes it possible to reduce the amount of memory that textures use by reducing the quality a little. This is useful if you're trying to cram as many textures as possible into a limited amount of graphics card and system memory, and is especially suitable for organic/nature textures where precision isn't paramount.

As an example, a 16-bit 1024x1024 JPG image requires 2.4 MB of graphics card memory. The same image stored in DDS format using DXT1 compression would require only 630 KB. So you could use almost 4 x 1024x1024 DDS textures for the 'price' of 1 JPG, so to speak.

Please note that DDS textures have to be a power of two, e.g. 8x8 pixels, 16x16, 32x32, 64x64, 128x128, 256x256, 512x512, 1024x1024, 2048x2048, 4096x4096 and so on.


LUMION 6.5 AND NEWER
Lumion 6.5 and newer support DDS BC7 format which is compressed at a ratio of 1:4 in the graphics card memory. Despite being compressed so heavily, the quality is excellent and it's hard to see the difference when you compare a DDS BC7 texture with the original uncompressed version.

To save a DDS BC7 texture, you'll need to install the Intelworks DDS plug-in for Adobe Photoshop. If your texture contains an alpha channel, it's very important that there is a Background layer in the Photoshop file before you save the DDS BC7 texture - otherwise, the exporter will skip the alpha channel.




LUMION 6.3 AND OLDER:
Lumion 6.3 and older support DDS DXT1/3/5 formats which use "lossy" compression methods. Lossy comrpession means that you will lose detail and colour information from your original texture. The compression ratio for DDS textures depends on which of the DXT1/3/5 formats you pick. Click here and read the sections on DXT1a, DXT3 and DXT5 to see which of the DXT formats to use when saving DDS textures.

If you'd like to save DDS textures for your Lumion materials, please note that you'll need Adobe Photoshop and Nvidia's DDS plugin for Photoshop.

You might notice that the DDS file size exceeds that of an equivalent JPG file. The reason is that JPG files are compressed files whereas DDS files are compressed in the graphics card memory, so you can safely ignore the DDS file sizes.




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