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Animated lights with motion blur not working correctly

Posted: Mon Jan 22, 2018 3:02 pm
by PHM
We are currently creating night-time scenes with vehicles moving fast - about 100kph, and seem to have found an issue with animated octane lights and motion blur.
Basically, the lights seem to behave the opposite of everything else.
When the camera is static but the vehicle is moving, the lights don't blur,when everything else has motion blur. The faster the vehicle. the more obvious it is, to the point that the light looks like it is moving away from the vehicle.
When the camera is attached to the vehicle, the lights blur when everything else is sharp.

Emissive textures work correctly.

I've made a simple test scene to demonstrate. The light on the left is a blackbody emission. The light on the right is a standard octane light.
1st, with the camera static
2018-01-22 14_59_39-Windows Media Player.png
blur lights.mp4
(1.57 MiB) Downloaded 1947 times
You can see the area light doesn't blur when the vehicle (red cube) moves.

2nd, with the camera as a child of the vehicle:
2018-01-22 14_59_11-Windows Media Player.png
blur lights 2.mp4
(1.65 MiB) Downloaded 1912 times
Now the area light blurs when the rest is sharp.


When exported as animated orbx and rendered in standalone, the behavior is correct, so I don't think it's an Octane thing:
2018-01-22 13_48_46-_C__Users_james_Desktop_blur lights.orbx - OctaneRender 3.07.png
We really need to get this fixed or figure a workaround as we are due to start work week.

Any ideas?


Demo file attached:
blur lights.zip
(122.56 KiB) Downloaded 126 times
A. Win 7
B. 980ti 6Gb/1080ti 11Gb
C. 64Gb
D. 385.28
E. 3.07
F. 3.07R2
G. C4D 18.057

Re: Animated lights with motion blur not working correctly

Posted: Mon Jan 22, 2018 3:58 pm
by aoktar
Motion is not implemented for lights so can't call it as BUG. You should use geometry+emissions with material rather than this way.

Re: Animated lights with motion blur not working correctly

Posted: Mon Jan 22, 2018 4:20 pm
by PHM
Hi Aoktar, it works as expected in standalone, is that a limitation in C4D or something?
2018-01-22 16_18_31-_C__Users_james_Desktop_blur lights 2.orbx - OctaneRender 3.07.png
Emission doesn't give the control we need - and changing to standalone a huge pain in our workflow.

Re: Animated lights with motion blur not working correctly

Posted: Mon Jan 22, 2018 4:29 pm
by aoktar
PHM wrote:Hi Aoktar, it works as expected in standalone, is that a limitation in C4D or something?
2018-01-22 16_18_31-_C__Users_james_Desktop_blur lights 2.orbx - OctaneRender 3.07.png
Emission doesn't give the control we need - and changing to standalone a huge pain in our workflow.
SA needs to know keyframes to generate motion blur. It's need to be implemented for transfering motion data frm c4d plugin. Without having this you can't get the effect. What's that you cannot control?

Re: Animated lights with motion blur not working correctly

Posted: Tue Jan 23, 2018 8:43 am
by PHM
We are dealing with lots of small lights with a throw of 100m or more, in specific patterns as specified by our client. We already have control rigs etc set up and lights behave 'better' at long distance. We are just able to get the right exposure and light patterns easier with lights than emitters.
We're looking at seeing if we can recreate the look we had with textures instead.

Thanks