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jeff prince

VW imageprops texture export issue or something more nefarious?

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I have some custom plants intermixed with stock VW plants(the ones in the rightmost rectangle)



When I export them to TwinMotion using C4D, note how some of the object have a black background where it should be transparent.



The image props were constructed by masking a photograph in Photoshop and/or Affinity Photo to create a texture and saved as PNG with a transparent background.  The imageprops were created in VW by using the aforementioned texture file with the options shown in these dialog boxes.



Everything behaves as expected in VW, but the black in place of alpha rears its head when VW is exporting the textures.

Note the image below.  On the left is how my plant with alpha appears outside of VW, as created by me.  The same plant as it appears as a texture exported from VW, either via extract image or C4D export.  The tree on the right is a default VW tree image prop exported via C4D.  




I suspect something is slightly different with the alpha channel or image definition, I just can't figure out why the images I am creating are behaving this way.  I'm beyond frustrated by this mystery.  Any help is appreciated.

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13 hours ago, jeff prince said:

When I export them to TwinMotion using C4D, note how some of the object have a black background where it should be transparent.



Interesting !

In my tests I have only seen NO transparency so far.

While in Enscape their transparency works out of the box.

So I thought Twinmotion would use other black/while mode

than Vectorworks.


Similar has been the case for C4D standard vs VRAY4C4D standard.

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I might be wrong, but it could be that your Mask Source should be Transparent Color...



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2 hours ago, Frank Brault said:

I might be wrong, but it could be that your Mask Source should be Transparent Color...



Thanks for the idea.  I have been using png with no background and an alpha channel

Here is a test with using the transparent color method, same result 😞

This is driving me mad...

Everything works as expected in vw.  I attached my test file below.



Imported into Twin Motion via C4D.... The image props I made in VW have issues, the VW plant does not.


transparency test.vwx

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so I did yet another experiment...

I compared the textures exported by VW to C4D, looking at both the composite alpha and background alpha channels.

In the image I prepared with a transparent background, the composite and  background alpha channels both indicate the cutout for a plant.

When I look at the same image generated by VW upon C4D export, the same alpha channels appear totally white, thereby generating the black boxes seen.

In the example below, I opened up the exported image for its texture, added the mask back in, resaved the PNG, and then reloaded the TwinMotion scene.  Magically, that plant now works (the other two plants with the black boxes are using different textures even though they look identical.

I think this gives a little weight to my theory that VW is doing something strange when exporting the textures.

That, or my process for creating images is flawed.

So here is my workflow for creating plant images.

  • take a photo of a real plant with my camera.
  • start with a blank psd file with a transparent background
  • paste in the photo I took
  • remove the unwanted pixles by erasing them, revealing the transparent backgound
  • save the psd and export a png file with its built in alpha channel
  • create an image prop in vw using the png file I just saved, using the mask from Alpha option.
  • export the model to C4D
  • import the C4D file into TwinMotion

The textures VW exports does not look like my source png files used to create the imageprop.  Confusion reigns.


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Hello jeff prince:

Can you attach the C4D file (including Textures folder for the C4D) you are importing into Twinmotion?


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@Dave Donley

Hey Dave,

Here are the attachments you requested.  


The procedure I used to create that imageprop of the hesperaloe is as follows:

1. start new VW document

2. "Create Image Prop" command

3. use the file imageprop-source.png as the basis for the prop

4. use default settings to create the imageprop and select "Use Mask" option - create mask

5. create mask from "reuse image from another resource - this prop's color

6. Source for mask = alpha channel

7. prop created


I created an all new test with a brand new image prop made from scratch using the imageprop-source.png file attached.

The other images were generated by Vectorworks during export to C4D.  You will note the source file has alpha channel and a clear background while the images created for the same plant has a black background in the exported texture.  That seems to be where the problem is.  It is also noteworthy that the default Vectorworks plant did not create this black background for the texture file.


I have 100s of custom plant images with alpha channels created like this sample which I hope to make custom plant object from.

Additionally, I am building a library of around 30 3D modeled plants that use images like this for textures that I hope to use for a custom library.  While most of these work fine within the Vectorworks environment, exporting to C4D is where the trouble starts.  My goal is to identify how to solve this issue so I can have a productive workflow to TwinMotion using my native and custom Vectorworks plants.


Thanks for any insights on how to fix this, including flaws in my process or source images.



Prop Ligustrum vulgare 0.9 S RT Color.png

Hesperaloe parviflora-1 Prop Texture Transparency.png

Prop Ligustrum vulgare 0.9 S RT Transparency.png

Hesperaloe parviflora-1 Prop Texture Color.png


Untitled 2.c4d Untitled 2.vwx

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The plants look fine in C4D I am wondering about the conversion from C4D to Twinmotion.  Maybe Twinmotion doesn't import them from C4D properly.


Does it matter if the image is set to Glow or not?  By default they have Glow so they have consistent flat shading.


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@Dave Donley

Thanks for looking into this.

The image prop I created automatically set Glow the same as the VW stock plant.

I also turned it off as a test, same result.  So Glow does not seem to be a factor.


I don't think it has to do with how Twinmotion imports the C4D based upon the test I did with my plants and a default Vectorworks plant.  In that example, the VW plant was fine in Twinmotion, but my plants are not.  Vectorworks seems to be changing my image file's alpha channel when exporting to C4D  format.  I'm fine with changing the way I make my plant images and textures, I just need to know the best practices before doing so.


Here is another example.  I purchased a textured 3D model of a plant in OBJ format.  It uses texture files, a base image and an alpha channel image.  When directly imported into Twinmotion, it looks fine.  When the same model is imported into VW with the same texture references, it too looks fine.  I hope to create a design in VW using this and many similar models.  However, when I export that same model from VW to C4D format and import it into Twinmotion, welcome back black boxes 😞  I think this further strengthens the argument that something is happening during the Vectorworks export process.


Here is the OBJ model loaded into Vectorworks, looks fine.  Note the use of alpha channels for the thorns and flowers




Here is the same OBJ model directly imported into Twinmotion.  Note how the thorns look fine and are using the alpha channel correctly.



And here is the OBJ imported into VW earlier and then exported to C4D format.  Note how the thorns and flowers now have black where they should be transparent.  The only thing I did was export it from VW....


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What does this attached file look like imported into TM?


If the alpha image is being imported correctly it should not matter what the background colors are in the color image.  The color and alpha are separate images.  If the alpha pixels are black then you should see clear - the alpha of the color image shouldn't matter because it is only supposed to use the RGB not the A.  The A comes from the alpha channel image which I think looks correct (white plant black background pixels).



Plant with Alpha.zip

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For this file I just used the alpha and color image files from VW exporting to C4D.  The color image and alpha image both have black background.


In your image above the two sides of the cube look dark.  (this is a C4D cube object)  Is there a control for "double-sided materials" in TM for the import?


If you want, I can look at a few example image props from your library to make sure they show correctly in C4D.



Screen Shot 2020-06-01 at 5.11.28 PM.pngScreen Shot 2020-06-01 at 5.11.25 PM.png

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@Dave Donley 

Why does Vectorworks add a black background to an image that originally had a transparent background?

This seems to be the source of the issue.


Here is the source files I used for the imageprop.  Note, it has a transparent background and an alpha channel.



Hesperaloe parviflora.png

Edited by jeff prince

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@Dave Donley


I'm at a total loss here.  It seems that VW export to C4D is doing something here.

In the example below, the plant with the black box is imported from VW->C4D export.  The two plants w/o the black box have been retextured in Twinmotion using my original png with transparency.  I don't know what goes into the programming of these tools, but it seems like it is a simple switch that is being flipped without my permission 🙂

Screen Shot 2020-06-01 at 4.31.47 PM.png

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The problem remains unresolved and I hope to hear an explanation.


Until it is resolved, I developed a work around involving a bit of unnecessary labor that I hope is eliminated.

I have to go into the texture folder that Vectorworks creates during C4D export and manually look at each texture to figure out which ones VW decided to modify by adding a black background.  I then take a copy of my master texture image used to create the plants, rename it to match the VW exported texture name, and replace the VW generated texture with my master.  This automatically loads in Twinmotion and I can then get to work.  Sure would be nice to know why VW is doing this in order to eliminate this unnecessary step.


Here's a test of the 3D plants I have been working on with the texture replacement work around I just described.  It's effective, but takes unnecessary time that the computer should do automatically.  I'm really just trying to develop a successful workflow to add fairly realistic 3D representation of my plants into Vectorworks Plant Objects and fulfill the promises of landscape BIM.  For this to be effective, the assets need to survive export to other rendering engines and then survive inevitable updates to the VW model exported back to Twinmotion.




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