Day 26

Wanted to do some test on caustics and how parameters in 'Caustic Light' and Mantra 'PBR' dramatically affects overall look & render time.

I went back to using the buddha .hip file from the previous day.

Experiment #1

The only change i made was the 'Sampling Quality' within my lights. Surprisingly, value of '1' and '10' had almost no impact on the renders.

In the 3rd image, Filter Sample parm in Caustic Light was increased to 128 from 64.

Rendering took approximately 8s more.















Experiment #2

'Pixel Sample' in Mantra.

Appears that this parm is very expensive, 3 x 3 to 6 x 6 and the render time was close to double.












Experiment #3

1st image was to see how the renderer react to photon counts. Increased it to 1 million compared to 2nd image which was 100,000 photons. Other parms remain the same for more accurate comparison.

I didn't feel it was an unreasonable increase in waiting-time considering the number of photons went up 10 folds.

Between 2nd and 3rd image, they had the same parms setting beside Reflect/Refract Limit.

Time taken was reduced by half upon lowering them to 2 from 10. Nice, doubt 10 is required in our project so this is going to help speed things up, every bit helps i guess.







Experiment #4

Diffuse Limit doesn't seem to make any changes. It may when other i am working on a heavier scene or other parms starts changing, we'll see.

1st image had 100,000 photons, typo there.











Experiment #5

Not exactly sure what 'Allowable Path' parm do or how it will help, green dots appeared after setting it to 'All paths' and render time x2.

Sorry, another typo in 1st image. It's 100,000 photons.

Hi Mr Ron, if it's convenient for you to explain. Thank you.








Experiment #6

Mantra > Render > Tile Size

Time taken as shown.




















Experiment #7








This one was more on see how Filter Sample affecting the look of caustics. Apparently it is like applying gaussian blur filter to it, they are getting less sharp and spreading outwards. (Appears more like glow effect than caustic to me)

Feel more confident about mantra and lights now, could probably answer or explain more if i am asked about various parameters.

My second time doing such experimentation, first was back in studio project as the computers had were much slower than FYP's and it had serious insufficient memory issues.

Batch renders would either abort or hang mid-way. Had to speed things up with optimization without compromising the quality, but i find it a less daunting task doing it in Houdini. Hope i aren't spending time researching at the wrong things. ><