Opacity tex comparison

[romullus]

I was making some foliage textures for personal use recently. Saved all maps to png format and begin to construct material. Soon enough i found that my material performs rather poor in therms of speed. Naturally, i blamed opacity map. Tried different tricks, but nothing really helped. So i decided to resave opacity texture to other format and to my surprise, i saw significant improvement. All other formats rendered much quicker... all except png and gif. Later i found out that transparency in those formats is what causing problems. But most interestingly is that gif saved without transparency shows massive improvement in render speed! So from now on, i'll use gif for opacity maps exclusively.

[Ondra]

this is interesting, can you send me this particular scene and the maps so I can run some tests?

[romullus]

Done!

[borisquezadaa]

Now that's something interesting!.

Good to know.

[Siahpoosh]

very useful , thank u

[steyin]

Curiouser and curiouser.

[kahein]

thank you for this, very useful

[Siahpoosh]

maybe this is because the informations in those formats , for example you will lost a lot of data in GIF file or u have more data in PNG file (RGB+alpha) somthing like this :
PNG(8bit) > BMP(8bit) > GIF

[Tweekazoid]

if you are interested in further testing, try comparing PNG with and without comprimation, as well as with and without interlacing...
I think the difference why it performs this way for each format is inherently in file format structure itself. Gif uses structure that can be read as 1 pixel at a time and does not relly on decoding other parts of file (with the exception of instructions). So my guess would be that it saves time by reducing the need for buffer. And maybe I am completely wrong

[Ondra]

If max REALLY decodes the original compressed format every time a texture is accessed, then I need to write CoronaMap ASAP. 

[rampally]

If max REALLY decodes the original compressed format every time a texture is accessed, then I need to write CoronaMap ASAP.

that's another great news Keymaster
i was supposed to ask this question today mean while i saw this .. great

[Juraj]

Definitely stirred my curiousity. I don't think there's way to measure this as easily in other renderers, to definitely pinpoint this as 3dsMax fault ?

And if so, I echo Tweekazoi's plea: Compare PNG based on comprimation (with and without), or alpha channel.

With Vray, I use purely .png for some sort of stuff(like foliage :- D), usually without comprimation, although over the time, I can't really remember if all of them are so.

[romullus]

I don't know what that comprimation is, you talking about, i guess it's compression, right? Anyway, i did some more tests as requested. Everything is saved from photoshop, source file doesn't contain any layers nor alpha channels (gif and png doesn't support alpha channel anyway). Bmp is provided for reference.
Results are quite confusing, at least for me:

[Ludvik Koutny]

I never ever used opacity from alpha. Always from an 8bit bitmap without alpha channel, so that's why i probably never ran into this issue.

I think that results of those tests are not confusing at all. They are actually quite simple to figure out. Best way seems  to be using 8bit opacity maps without any alpha channel.

[romullus]

Rawalanche, all these maps are 8 bits without alpha channel.