View Full Version : estimate rendering time

03-12-2003, 01:30 AM

Do you have some tips how to estimate rendering times in LW? I am rendering stilllifes so just 1 frame.

Thank you

03-12-2003, 02:31 AM
Hi Marci,

Do a lores preview and multiply your rendering time by the scale factor squared.


Original Size: 1600x1200
Lores: 400x300
Scale factor = 4 (1600/4 = 400)

Render time = lores time * 4 *4 = lores time * 16

Basically because in this case the original size image has 16 times as many pixels as the lores version.
You mileage may vary though.
A complex setup, raytrace optimization and many shadow maps will take the same time to prepare on both scenes (the "moving polygons" stuff). So in this case the final time will probably be lower than estimated.
If you run out of RAM due to the high res, the final time will obviously be higher.

But the above way is a decent rule of thumb.


03-12-2003, 03:07 AM

I tried what you mentioned but i think the higher detail in the final image is also bigger than in the lo-res rendering. It have to render more than "just", as you mentioned 16 times. You tried your method, am i right? I tried also to render just a small part of the image which includes some reflections. I rendered it in lo-res and also in the final resolution. The difference is never linear. This why i compared the linear result for example 200s x 16 = 3200s and real result was done in 4000s.
The difference is 4000/3200=1.25. This number is multiplied with the linear result of the WHOLE image.

For example:

lores full frame takes 1000s x 16 x 1.25 = 20000s = 5h 30m

What you think?


03-12-2003, 03:18 AM

as I said, your mileage will vary :) Antialiasing will play a big part too. But if you have a correction factor like 1,25, you can still do a pretty decent estimate.

Better than nothing :) I guess if you're using 1,5 you'll be on the safe side (important when talking to customers...)


03-12-2003, 03:30 AM

The truth is that i wanted to know if i start rendering at midnight, the final image will be done before 5:30. So when I wake up to work I can see the final image even my eyes i tired :) I think the way trough corrections should work.

I try another combinations.

If i will know something new i let you know.


03-12-2003, 12:39 PM
Estimate Time to Completion


This should do the trick!!


03-12-2003, 12:51 PM
there's also a freeware applett called "ETR" wich is pretty handy as well...
Also, if you're doing a single image, you can break up the image into segments(via plugins) and render multiple segments.

03-12-2003, 02:04 PM
thanx for those, but animation is even bitchir (on purpose) since everthing changes but you wouldnt care right (im post whoriing)


03-12-2003, 10:37 PM
Hello again,
I think, I find it out. To find the most correct time is to render the whole image! But we dont really want it so correct, am i right?Than I prepared a mask in Adobe Illustrator which is a black rectangle with cut out parts. You can figure out how much covers the holes. For example I prepared 800x600 black rectangle with 50 20x15 cutouts which have area 15000. The are of the 800x600 is 480000. So 480000/15000=32. After I used this 2 color image as a foreground image in LW-composite and set the low and the high key to 255,255,255 or the color of the cutouts. Render the image in the final resolution with the mask and multiply the rendering time with the factor number 32.

You can experiment with more and smaller cutouts or the opposite.

I tried also the 64 factor but it was really too close.