Bug #546

Collada material properties incorrect for transparent objects

Added by Jonas Hauquier over 4 years ago. Updated almost 2 years ago.

Status:AcceptedStart date:10/06/2014
Priority:NormalDue date:
Assignee:Joel Palmius% Done:

0%

Category:File export
Target version:MakeHuman 1.1.2

screenshot_1_1414902889.png (194 KB) Rob Baer, 11/02/2014 05:35 AM

screenshot_1_1414931090.png (771 KB) Rob Baer, 11/02/2014 01:25 PM

3DS_ColladaImport.txt Magnifier (18.7 KB) Rob Baer, 11/02/2014 10:51 PM

screenshot_2_1414965139.png (414 KB) Rob Baer, 11/02/2014 10:53 PM

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Related issues

Related to MakeHuman - Bug #381: Exporters - Testing of new export configurations New 05/16/2014
Related to MakeHuman - Bug #624: Blender Collada import has problems with rigs New 11/02/2014
Related to MakeHuman - Bug #468: Eyes not exported correctly to FBX Fixed 07/24/2014
Related to MakeHuman - Bug #878: Document and/or fix the process from MH to Blender (parti... New 05/28/2015
Related to MakeHuman - Bug #1148: Test/fix collada pipeline vs various external platforms New 03/12/2017

History

#1 Updated by Rob Baer about 4 years ago

I have spent some time testing collada throuput from MH to Blender using .dae/collada. I don't yet have answers at the collada xml level or a division of mh exporter vs Blender importer deficiencies. However, I have determined some standard changes that can be made in Blender material and texture panels to have a reasonable facimile in Blender of what leaves MH. These settings need to be made to the transparent materials and the body skin. These include: body, eyebrows, eyelashes, high poly eyes, (untested low poly eyes), and hair. The changes can be made to tongue and teeth without harm, but it seems these render fine without the changes. The changes to the body/skin end up ultimately helping with proper eyebrow display.

1. Export an MH with geometries as collada and import into Blender 2.72 as collada
2. Make the following changes to MATERIAL for each geometry asset (and the body; probably would apply to a topology too?)
  • Check transparency to enable it
  • Move alpha slider and specualr slider under diffuse to 0 (not its current 1.0)
  • Under Shadow, check receive transparent.
    3. Under TEXTURE make the following change
  • Under the Influence Diffuse section, check alpha in addition to color (already checked)

There may be some additional benefit for reducing the spectral intensity from 1.0 to 0.4 or lower for the high poly eyes. This seems to make nicer reflections at outer edge of iris. This probably means an update to the material file for the high poly eyes.

#3 Updated by Jonas Hauquier about 4 years ago

Why would you enable transparency on the body? That doesn't sound right. Think of the performance hit in rendering that this will cause.

#4 Updated by Rob Baer about 4 years ago

I was stupidly trying to reduce it to a single group of settings without considering performance. It is not necessary to turn on transparency for body, but it might be necessary to enable "Shadow - receive transparency". The result seem slightly better than turning off 'cast shadows' for hair, eyes, eyebrows, and eyelashes.

(The blonde hair material may have been an extreme test because it is less sensitive to some changes and more sensitive to others than the black hair material. The blonde hair material may even benefit from shaderless)

More pictures :

#5 Updated by Jonas Hauquier about 4 years ago

I think disabling shadow casting for hair looks better.
Some AO under the head hair might be good though.

#6 Updated by Jonas Hauquier about 4 years ago

  • Related to Bug #381: Exporters - Testing of new export configurations added

#7 Updated by Jonas Hauquier about 4 years ago

I think your collada transparency issues are due to a bug in the blender collada importer: https://developer.blender.org/T32392
Note that the ticket has been open for 2 years already, with no significant changes.

What really worries me is the remark here: https://developer.blender.org/T42327

"We don't currently have collada maintainer, so thanks for the report but moving it to the todo list" 

#8 Updated by Jonas Hauquier about 4 years ago

  • Related to Bug #624: Blender Collada import has problems with rigs added

#9 Updated by Rob Baer about 4 years ago

I think your collada transparency issues are due to a bug in the blender collada importer: https://developer.blender.org/T32392
Note that the ticket has been open for 2 years already, with no significant changes.

Worrisome indeed! In fact, my attempts to Export a "fixed model" as collada from Blender and re-import it into Blender do not result in the fixes being retained.

#10 Updated by Rob Baer about 4 years ago

Take this comment with a "grain of salt" because I know next to nothing about 3DSMax, but I tried importing a couple of MH collada exports into Max 2014.

The simpler file produced a couple of warnings, but the 2nd file, which had the new skeleton, seemed to produce numerous warnings -- a warning per bone, and a rather scary looking viewport with "connected Edges" around the model. The warnings associated with the import of the two files are in the attached text file.

#11 Updated by Jonas Hauquier about 4 years ago

Rob Baer wrote:

my attempts to Export a "fixed model" as collada from Blender and re-import it into Blender do not result into the fixes being retained."

That's confirmed by the roundtrip issues in the TODO: http://wiki.blender.org/index.php/Dev:2.5/Source/Development/Todo/Import_Export#Export:_Bugs
Notably: https://developer.blender.org/T32549

Messages like:

"Moving opencollada bugs to TODO has been done since this has so far not yet been effectively maintained.

This is not a step to remove collada support, however if in the next year there is little work done in this area we may have to reconsider." 

Don't exactly inspire much trust in Blender's commitment to collada.

From this same TODO page:

"Short term goals (Blender 2.64):
Make export and Import more robust. Idealy reimport of an exported collada file should recreate the original data." 

But it seems like this short term goal has still not entirely been reached in 2.7

Earlier this year the proposal has been launched to rewrite the collada exporter, which currently is part of the Blender C code, in python: https://developer.blender.org/T41071
This could breathe life again in collada support, and make the importer/exporter more maintainable.
But as of yet there have been no takers.

#12 Updated by Jonas Hauquier about 4 years ago

Rob Baer wrote:

Take this comment with a "grain of salt" because ... 3DSMax ...

Yes of course. The more general problem is that collada really never managed to take off as a well supported format, at least not for DCC tools. Many people regard it as a silly format "only used for games", collada's reputation suffering from many broken or non-standard implementations, notably in games (requiring many custom hacks to make them work for a specific engine -- for example Second Life).

For exchange between DCC tools, the battle has long been won by the FBX format. FBX has its own problems, as it is no open format and Blender's support for it -- while getting pretty good recently -- is largely thanks to reverse engineering efforts.

But if it works...

#13 Updated by Anonymous about 4 years ago

  • Assignee set to Jonas Hauquier

#14 Updated by Jonas Hauquier over 3 years ago

  • Related to Bug #468: Eyes not exported correctly to FBX added

#15 Updated by Rob Baer over 3 years ago

  • Related to Bug #878: Document and/or fix the process from MH to Blender (particularly cycles) added

#16 Updated by Aranuvir # almost 2 years ago

  • Target version set to MakeHuman 1.2.0

#17 Updated by Joel Palmius almost 2 years ago

  • Category set to File export
  • Assignee changed from Jonas Hauquier to Joel Palmius
  • Target version changed from MakeHuman 1.2.0 to MakeHuman 1.1.2

Going to take another look at this to see if the situation has changed.

#18 Updated by Joel Palmius almost 2 years ago

  • Related to Bug #1148: Test/fix collada pipeline vs various external platforms added

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