im just wondering what .rat does and why you can't can't just use standard images for materials and background images?

It's explained in the docs:

http://www.sidefx.com/docs/houdini10.0/io/formats/image_formats [sidefx.com]

when Houdini render it internally make them .rat
you don't need to change them.

http://www.sidefx.com/index.php?option=com_forum&Itemid=172&page=viewtopic&t=17103&highlight=rat [sidefx.com]

pelos
when Houdini render it internally make them .rat
you don't need to change them.

http://www.sidefx.com/index.php?option=com_forum&Itemid=172&page=viewtopic&t=17103&highlight=rat [sidefx.com]

It's still better to use them since
- The conversion is done on every render
- You don't get the benefit of paging of files
- You don't get the benefit of paging memory

For example, when rendering with a .rat file, only the parts of the image that are needed are loaded in. If the image is converted by mantra, the entire image is read and converted. In many cases this doesn't make a big difference. When dealing with very large numbers of large sized texture maps, you might notice a performance hit.

pelos
when Houdini render it internally make them .rat
you don't need to change them.

http://www.sidefx.com/index.php?option=com_forum&Itemid=172&page=viewtopic&t=17103&highlight=rat [sidefx.com]

but this way, you won't see any advantage of rat files at all, since Mantra will have to load a whole file into memory in order to convert it, second it will do it every single frame (try to convert a couple of <100MB textures to see disadvantage of that scenario), So manual conversion is really good option I'm afraid, what can be pretty tedious without proper setup, like a bunch of scripts for updating *.rat directory after any texture source was changed and such…

btw some studios have a system which finds images in a scene sent to a farm, and converts&replaces textures in place. It can be tricky though… ideally some hook on mantra's side would be helpful (like arbitrary command execution on any file accessed by mantra, what would allow setup cache system among other stuff).


EDIT:ups, Mark was faster…

You can use Houdini's internal compositor to convert your images to .rat and automate most of that.

“btw some studios have a system which finds images in a scene sent to a farm, and converts&replaces textures in place. It can be tricky though… ideally some hook on mantra's side would be helpful (like arbitrary command execution on any file accessed by mantra, what would allow setup cache system among other stuff).”

wow thats Cool .

thanks for all the tips guys.