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View Full Version : VPR better than the final render?!?! LW 11.6



starbase1
05-19-2015, 10:04 AM
I'm working on a scene with very complex lighting, and have been struggling, Then I happened to notice that the VPR preview looks better than the final render!

See attached image. VPR at the top, final render below.

The main things that I see here are:


Artefacts in the volumetric shadows - see the top ship shadow.
Light getting into the intakes, (not sure how).
And even some fairly well exposed surfaces becoming a lot lighter.



Anyone got any ideas what might be going on?

And how I can get a render that looks like VPR?

LW11.6

Nick

Sensei
05-19-2015, 12:21 PM
What are VPR options? Draft? Half res?

What is Ray Recursion Limit?

Are you using 3rd party lights?

Are you using GI?

How about multi-threading? Tried rendering single thread?

Kevbarnes
05-19-2015, 12:24 PM
Anyone got any ideas what might be going on?

Are you using global illumination?, you may be getting secondary bounces as all the main drop shadows are being filled in.

Sensei
05-19-2015, 12:48 PM
Do you noticed lights on the left? They are also different.. F9 render are brighter, and more round.
The same with lights below spaceship.
In VPR they look like white polygons, while F9 equivalent are glowing.

starbase1
05-19-2015, 02:51 PM
128318Thanks to all for the input, I worked it out!

I switched from shadow maps to ray traced - render times went up, but that did the trick.

I still find it interesting that the preview render was better that the real thing first time around. This rather suggests that VPR was not using shadow maps...
It's definitely one to be aware of as I have previously assumed that it was pretty much straight - though I think it uses fairly agressive adaptive AA, judging by the way fine detail sometimes goes missing...

Sensei
05-19-2015, 03:00 PM
VPR Draft Mode is cutting Ray Recursion Limit at 2 or so.

jwiede
05-20-2015, 09:11 PM
I still find it interesting that the preview render was better that the real thing first time around. This rather suggests that VPR was not using shadow maps...

That's a bit of an annoying omission if VPR doesn't use shadow maps even when that's how the scene is configured. Unless maybe LW3DG thought nobody used shadow maps anymore? Still...

Is there any single place in the documentation enumerating everything VPR can and cannot preview properly? If not, there really needs to be such a listing (incl. index references). Also, would it really be so difficult for VPR to log in console or such any elements which are currently enabled/active in view, and which it cannot preview properly? At least that way, in cases like this, one could consult the log to see if VPR had chosen to omit any scene elements/settings that might cause a difference in appearance.

In general, LW seems to have a LOT of room for improvement when it comes to reporting problems to users, instead too often preferring to fail silently or just ignore problem inputs/operands (versus reporting them somehow).

creacon
05-27-2015, 07:34 AM
They should just throw shadow maps out, the only use they have is backwards compatibility.
If you're still using shadow maps stop now! :)

creacon

zardoz
05-27-2015, 10:51 AM
Is there any single place in the documentation enumerating everything VPR can and cannot preview properly? If not, there really needs to be such a listing (incl. index references). Also, would it really be so difficult for VPR to log in console or such any elements which are currently enabled/active in view, and which it cannot preview properly? At least that way, in cases like this, one could consult the log to see if VPR had chosen to omit any scene elements/settings that might cause a difference in appearance.
In general, LW seems to have a LOT of room for improvement when it comes to reporting problems to users, instead too often preferring to fail silently or just ignore problem inputs/operands (versus reporting them somehow).


you have that list on the manual on page 2158:
"VPR Draft Mode Limitations
VPR’s default Draft Mode is designed to show you renders as quickly as possible, however it doesn’t
support everything that VPR is capable of. Here’s a list of VPR Draft mode limitations:
• Photoreal Motion Blur is disabled
• Depth of Field is disabled
• Advanced/custom cameras are disabled
• Stereo rendering is disabled
• The adaptive threshold is set to 0.1
• Minimum Samples is set to 1 and Maximum Samples is 9
• Oversampling is set to 0.5
• Undersampling is set to 4 pixels max (disabled in full rendering)
• Adaptive Sampling uses a 2.2 gamma function rather than the output color space to
determine the brightness difference.
• Shading Samples are limited to 4.
• Ray Recursion Limit is set to 4 but the maximum reflection rays is set to 2.
• The max GI ray bounces is set to 1
• The GI Use Transparency, Directional Rays and Use Bumps setting are disabled.
• The GI Rays Per Evaluation setting is limited to 32/16 when interpolating and 4/4 when
sampled."

cheers

Danner
05-27-2015, 11:03 AM
I love shadow mapped lights!
I use them all the time. There isn't a soft shadow casting light that comes even close to this render speed. Specially if you activate their cache. I know they can cause jagged shadows and they don't take transparency into account, but they are still a useful tool.

spherical
05-27-2015, 02:39 PM
And they don't do contact shadows well, if at all.

zardoz
05-27-2015, 03:35 PM
I haven't used shadow mapping in more than 10 years...

jwiede
05-27-2015, 09:12 PM
you have that list on the manual on page 2158:
"VPR Draft Mode Limitations
VPR’s default Draft Mode is designed to show you renders as quickly as possible, however it doesn’t
support everything that VPR is capable of. Here’s a list of VPR Draft mode limitations:
• Photoreal Motion Blur is disabled
• Depth of Field is disabled
• Advanced/custom cameras are disabled
• Stereo rendering is disabled
• The adaptive threshold is set to 0.1
• Minimum Samples is set to 1 and Maximum Samples is 9
• Oversampling is set to 0.5
• Undersampling is set to 4 pixels max (disabled in full rendering)
• Adaptive Sampling uses a 2.2 gamma function rather than the output color space to
determine the brightness difference.
• Shading Samples are limited to 4.
• Ray Recursion Limit is set to 4 but the maximum reflection rays is set to 2.
• The max GI ray bounces is set to 1
• The GI Use Transparency, Directional Rays and Use Bumps setting are disabled.
• The GI Rays Per Evaluation setting is limited to 32/16 when interpolating and 4/4 when
sampled."

If you read more carefully, that's a list of the differences between VPR's draft mode and "full" (non-draft) mode renders. That's not what I requested, I requested a list of the all the cases where VPR cannot (even in "full" mode) properly represent the visual contribution of a feature/entity, yet an F9/F10 render does represents its visual contribution. Shadow maps are one such case, certain nodes (IIRC) do not render the same/properly when using VPR versus an F9/F10 render and thus are another. What I'm asking for is unrelated / orthogonal to the list of cases where draft mode VPR has issues and "full" mode VPR does not have the same issues. Thanks, though!

lardbros
05-28-2015, 06:09 AM
I'm pretty sure that the list is:
-Shadow maps
-Any node that does a pre-processing pass

They are the only ones I've found/heard about

Netvudu
05-29-2015, 06:41 AM
I haven't used shadow mapping in more than 10 years...

Indeed, and you haven´t because regular shadow maps are old and clunky. Now, if we could depth shadow maps, the way Houdini´s Mantra does them, you get shadow maps that DO respect transparency...does it make them cool for everything? No. Are they useful? gods, yes. For starters, they give HUGE speed ups for volume rendering....hello hypervoxels.

zardoz
05-29-2015, 07:25 AM
Indeed, and you haven´t because regular shadow maps are old and clunky. Now, if we could depth shadow maps, the way Houdini´s Mantra does them, you get shadow maps that DO respect transparency...does it make them cool for everything? No. Are they useful? gods, yes. For starters, they give HUGE speed ups for volume rendering....hello hypervoxels.

I have to check that then! thanks

Netvudu
05-29-2015, 08:25 AM
it would be nicer if we could check it inside Lightwave...*shrugh*