Progressive renderer not clearing ? hdri light weirdness.

[anthonyh]

hi tashko,
thanks for the investigation. to be honest i didn`t know trace reflections was off. it wasn`t by choice. maybe happened from a vray scene convert ?
i`ll also sort a scene out where motion blur goes nuts and send when i have a little time.
thanks
anthonyh

[tashko.zashev]

hi tashko,
thanks for the investigation. to be honest i didn`t know trace reflections was off. it wasn`t by choice. maybe happened from a vray scene convert ?
i`ll also sort a scene out where motion blur goes nuts and send when i have a little time.
thanks
anthonyh

Probably Turn on trace reflections when converting Standard materials was not enabled ?

[anthonyh]

hi,
yup that was probably it.
thanks
anthonyh

[anthonyh]

hi tashko,
just an update that i`ve sent a scene where the teleporting geometry with motion blur occurs to support. we`ve had quite a few times when knocking a scene together and either the scene scale is probably too large or the dummy linking movement is travelling too fast(for real world comparison). the result is teleporting geometry where the rotor blades of a helicopter don`t stay in place and spin but shift out of place and smear. also had it recently where the non-motion blurred geometry also shifted across the world compared where it should be. i`ll dig that out and send along in case.
thanks
anthony

[tashko.zashev]

hi tashko,
just an update that i`ve sent a scene where the teleporting geometry with motion blur occurs to support. we`ve had quite a few times when knocking a scene together and either the scene scale is probably too large or the dummy linking movement is travelling too fast(for real world comparison). the result is teleporting geometry where the rotor blades of a helicopter don`t stay in place and spin but shift out of place and smear. also had it recently where the non-motion blurred geometry also shifted across the world compared where it should be. i`ll dig that out and send along in case.
thanks
anthony

Hi again and thanks for the scene file. I think this is a bug but need more time for investigation, however I see that Camera motion blur from the Render settings > Camera is Off. When enabled, the results I'm getting is correct. Would you please confirm this at your side ?

[anthonyh]

hi tashko,
no, it renders wrong for me. however just rechecking it now it seems i messed up the scene i sent slightly. i added a teapot to the bottom of the rotor to represent helicopter position but i forgot to link it to the main moving dummy. at frame 26 it appears where it should and you can link it to the movement dummy. once linked ticking camera motion blur on does indeed fix the rotor position but the teapot(helicopter) now moves and motion blurs across the screen as well, even though in vray properties it is set tick off and 1 sample for motion blur to set motion blur off.
i`ve resaved it with teapot attached and have attached the file..rotor test 2.zip
also this is what i get..

thanks
anthonyh

[tashko.zashev]

I see, but in this setup the Teapot has one MB geom. sample (use Default mb samples is off)

Enabling Default moblur samples will fix the wrong MB result of the Teapot since it takes the value form the Camera render settings (Geom. samples 12)

[anthonyh]

hi tashko,
i thought this was the way to turn off motion blur for an object (tick off, samples to 1) ? i only want the rotors to be motion blurred *not* the helicopter. i can see turning the tick back on does solve the teapot location issue but it`s also now motion blurred from camera movement which i don`t want. is this not possible to have some motion blurred objects and some not ? or is there another way i can achieve this ? i presume you`re allowed to turn off the camera motion for this reason, to have motion blurred objects with no camera blur ?
this method has certainly worked in many other scenes for this, just not some scenes which have this issue.
i`ve dug out another example of this (i believe it`s a related issue). it`s generally the same setup however it shows the teleporting geometry better as i`ve set it back to default vray properties tick on/mb samples 2. i have both motion blur and camera motion blur off. now render frame 0 and there`s the plane where it should be. now render frame 20, the plane is now not where it should be. now render frame 60, the plane is completely gone from frame. this seems like a similar issue ?
thanks
anthony

[tashko.zashev]

Hi again.

Actually I didn't find any problems in the way V-Ray calculates the motion blur for this setup.
I'm attaching one render result with scene rotor test 2.zip
where the only thing I changed was Default moblur samples to On.

Here V-Ray calculates MB (using enough Samples) for all objects in the scene and takes into account the camera movement as well (Camera motion blur enabled).
This MB result looks correct to me and exactly what you want to achieve, please correct me if I'm wrong ?

i thought this was the way to turn off motion blur for an object (tick off, samples to 1) ?

Yes, that the case if you need to remove the blurry effect of a moving object, but in this setup you will still get motion blurred Teapot due to the camera motion blur calculations. This is the reason why in this setup you get unexpected render result.
The same occurs for the Rotor animation. Disabling the Camera motion blur will lead to MB calculations of the Rotor rotation (dummy 1) and movement according to the camera view.
I think this will answer the other questions you have noted in the last reply.

[anthonyh]

hi tashko,
please note: i`m using camera005 not the physical camera `physcamera001`
i don`t want motion blur on the teapot but i do want motion blur for the rotors i.e spinning correctly and the rotors to be in the correct position above the teapot and i can`t make that work.
* your suggestion of turning the tick box on and leaving samples at 1, the teapot is still motion blurred which i don`t want, it`s less obvious but it is still clearly motion blurred. i don`t really want to use camera motion blur. i also don`t want motion blur on the teapot only on the rotors spinning in place.

see rotorscene.zip attachment, it`s a movie of the viewport grab. there is very little camera movement, a slow zoom in.
these images are what you see when from rendering combinations of use default mb tick on/off, cam mb on/off:





none of the above is what i need, some of them just look plain wrong when compared with what you`d expect the scene to look like compared with the attached movie. the camera movement is a slow zoom in yet the objects are shifting way out of position when using different combinations of these settings.
again what i`m after is the rotor spinning correctly with motion blur as if it`s spinning and in place. i also want the teapot to have *no* motion blur. is this possible ? because i cannot make it do that.
- please also see the other scene i attached in an earlier post takeoff.zip. there is no motion blur in this scene but geometry is flying out of place the further into the animation you go until it is completely missing. file is in post #23. scanline and mental ray render this in position correctly, vray does not. i`m curious if it does the same for you ?

i understand that some of what`s happening might be the way vray technically handles this scene but when you look at the viewport movie it should be fairly obvious what i want to happen but it doesn`t. teapot with no motion blur and rotors spinning above it correctly.
sorry for the long winded post.
many thanks for your patience,
anthonyh

[tashko.zashev]

Thanks for adding more details to this.

Unfortunately there is no option to control the Camera motion blur per object and that was the reason why I suggested the MB setup in post #24.
Probably another solution would be to render the Rotor and Teapot separately and then combine everything in post.

- please also see the other scene i attached in an earlier post takeoff.zip. there is no motion blur in this scene but geometry is flying out of place the further into the animation you go until it is completely missing. file is in post #23. scanline and mental ray render this in position correctly, vray does not. i`m curious if it does the same for you ?

It's the same here. Seems to be an issue with the Camera motion blur samples (V-Ray object properties) when set to 1 for the render camera. Please put more samples there to get it working as expected.
I've send a bug report to our developers about this and will post here as soon as any new information is available.

[anthonyh]

hi tashko,
darn you beat me. i was just putting together a screen grab vs render to show off the moving geometry problem ! heh
anyway glad you found the cause. when trying to set the objects to not have motion blur i`ve obviously also set it for the camera, i didn`t know you could do that.
at least i can sort it for now in our scenes.

As for the motion blur i`m trying to control object motion blur per object, i never use camera motion blur. i prefer to add that in post to keep render times down with velocity channel and reelsmart. it`s not as good as in camera but it means i don`t need to rerender if it`s too heavy/light.
The strange thing is it only happens in certain scenes. i`m fairly certain it`s to do with the movement speed of the dummy moving the helicopter being too fast in scene. however relative to the camera view it`s moving slowly in view. it`s like the world movement scale is affecting the motion blur even though relative to the camera the movement is small.
The only way i`ve been able to get around this is to keep the helicopter still and move the scenery beneath it but it`s a bit of a bad fudge vs flying the helicopter around in scene.
anyway 1 issue down.
thanks again
anthonyh

[tashko.zashev]

For this specific animation setup you have to keep object MB and Camera MB active to get the Rotor MBlured and in position, while the Camera MB makes the really small MB effect to the Teapot due to the slow movement towards the camera view.

[anthonyh]

hi tashko,
i noticed the motion blur was reduced by using camera motion blur but i was told it needs to be off because it looked slightly blurry. i had to agree as it doesn`t look completely crisp so i removed the helicopter movement and animated the scene around it instead. i could also composite it true, that`s another solution but it adds the complexity of having to render 2 scenes instead of 1(i know not a huge thing but with multiple scenes it adds up). to be honest neither solution is ideal but then there`s always some challenge every day !
i just think it`s odd that i can`t get this to work. i get that it`s just probably how vray works, it`s just from a visual point of view it doesn`t seem to do what *i`d* expect it to do with only object motion blur active on the rotor given the animation i see in the viewport. ie spinning rotor and unblurred teapot. that`s obviously only *my* expectation and i guess vray just doesn`t do that.
thanks again
anthonyh

[tashko.zashev]

Hi Anthonyh,

I just want to let you know that the next V-Ray 3.5 beta will have a fix for the issue with noisy progressive renders and subpixel mapping enabled.