GI questions: Light Cach Prepass? Camera Path?

[Ihno]

Hi,
I have some questions about the GI:

First question:
If i have an animation with moving camera, objects and lights, i have to precalculate the Irradiance map with "Use Camera Path" checked.
So far so good, i take the Animation Prepass Mode check "dont render final image" and if i hit render it generates a Irradiance map file for every frame, very similar to Mentalrays Final Gather.
But what is with the Light Chach?
If i use the single frame mode it just creates one Light Cach file and overrites it after every frame, the file dosen´t seam to grow, so i think there is only the information about the last rendered Frame in it.
But i whant to generate the whole Light Cach for the entire animation during the Irradiance Prepass, thereby no precalculation has to be done twice.

Second question:
What if i have an object linked to the camera? Like a weapon in a egoshooter or a plane cockpit. If i use "use camerapath" it seams to regerads just the camera movement withot the movement of the objekt linked to it.
Couldn´t this create manny artefacts? And if not, what sense makes it to precalculate things that never´ll be rendered like that?
Is it better to turn "use camerapath" off for that kind of scene?

[Svetlozar Draganov]

Light Cache uses different approach and it cannot be saved for every frame like Irradiance Map.

The good news however is that the Irradiance Map could store the Light Cache(Brute Force) information into itself and you could disable secondary bounce engine for the final rendering, just load the IM from file it will contain the information for both primary and secondary bounces.

According to the linked to the camera question - I haven't test this before but I don't think that using "use camera path" option will introduce any artefacts.
Use camera path option could be still useful since not all objects will be linked to the camera.

[Ihno]

I haven't test this before but I don't think that using "use camera path" option will introduce any artefacts.

As i thought, it produces heavy artifacts, they are looking like Photon disks i used a irradiance map with Brute Force for the secundary bounces.
So i have to do it without Camera path and hope it don´t flicker to mutch...

Maby this could be a Feature in the next release... a checkbox to regard the Camera´s hierarchy, preferably in both directions, camera as child or parent.

[Svetlozar Draganov]

Would it be possible to send us a stripped down version of the scene and some already frames containing the artefacts you are talking about.

[Ihno]

Well iam not shure about that anymore, got similar artefacts without camera path checkt.
Iam doing something wrong, i think i have to read the manual again
This is what iam doing:
1: Set up irradiance map and brutforce in singleframe mode.
2: Change the irradiance map mode to animation prepass.
3: Hit render
4: change the irradiance map mode to animation rendering turn off bruteforce by selekting "none" for sencundary bounce engine. And hit render again.

I got also a error in some sequences when i try to render the image after the Prepass:
UNHANDELT EXEPTION: Image prepass
Last Marker is at ./src/globillummap.cpp, line 1563:
GlobalIllumMap::buildLightMap() {1}
Please note that although this error is generated by V-Ray... and so on.
Here is the logfile:
vraylog.zip

I will upload picture and scene later.

Thanks

Edit: here is a Picture:



Edit2:
another question:
If i get a good result with 100 interpolation samples on the irradiance map in the single file mode,
i can turn it down to 20 if i render the Animation because it will take 5 prepass maps to interpolate when interpolating Frames ist set to 2 right?

[Svetlozar Draganov]

Thanks for the update.

1.We will need a scene in order to find out what cause the crash.
2.The end result between the Single Frame and the Animation Prepass/Rendering is different and it is not guaranteed that the decreasing Interpolation Samples value 5times will maintain the same quality.

[Ihno]

Hi,
after i read some tutorials, i changed many things and get rid of that chrash. Don´t ask me what it was.

But now there is a new one, if i do a prepass and try to render after that, it tells me: "error: This irradiance map cannot be uset in animation mode"
I used the animation prepass mode and after that the animation rendering mode.

Here is my Scene:
S1_T07_01.zip

[Svetlozar Draganov]

I've just run a quick test and it worked fine here.
I have pre-calculated IM for frames 570-580, then switched to rendering mode and I rendered frame 575.
All IMs were loaded correctly.


Can you send us a step-by-step instructions what we should do in order to reproduce the issue into our environment and with which V-Ray/3DSMax version.

[Ihno]

I tryed 3ds Max 2014 (SP5) and 3ds Max 2015 (SP2) both with V-ray 3.0007 and on 2 different machienes (i7/i3 12gb Ram each) with "use camera path" and without "use camera path".
I also tryed to save the map files local. And i tryed to leave the light cache on for rendering.
What i don´t have tryed is, to merge the Scene in a empty one and set it up again.
That is the last thing i could think of, except asking you guys.

This is what iam doing:

1. Make shure the animation prepass mode is on and light cache is activated.
2. After generating some map files, switch to animation rendering mode turn off Light Chach by selecting none for secundary bounce engine and hit render again.

Can this be caused from the textures or the IES file?
The strange thing is that i already rendered the first 700 frames and everything worked fine...
Some settings changed and some Objects are hidden now but the assets (Textures, IES) are the same...

I think i have to check them all.
We had problems with our server and maby the IES or a texture is broken,
i think i would get get an error message if i render it in the single fame mode... But everything seams to work Fine.

[Svetlozar Draganov]

I did another test following your instructions, with the same versions of Max and Vray but again I couldn't reproduce the issue.
This time I have precalculated IM for frames 1000-1010 and rendered the middle frames.


Would it be possible to send us a few of the IM-caches generated in your environment or pack the entire scene?

[Ihno]

I reinstalled my system and now it works. I dont know what it was, but my pc did strange things in the last vew days.
This dosent explane why i got this error on a second mashine but... what ever, the Problem is solved.

[Svetlozar Draganov]

Glad to hear it works now.
Feel free to contact us if it happens again.