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    Alpha Channel, Trees, Vray - HELP

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    • C Offline
      CurryPork
      last edited by

      Hi forum, I need some alpha channel help. I don't know if it's a Vray setting or a Sketchup setting.

      Basically, I have some 2D and 3D trees sketchup trees, but I cannot get them to render correctly in VRAY for sketchup. How can I fix the alpha channel?

      Thanks


      2D Tree


      2D Tree rendered in Vray


      3D Tree


      3D Tree rendered in Vray

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      • thomthomT Offline
        thomthom
        last edited by

        You need to extract the alpha channel as a grayscale image. Then add that to the transparency slot in the diffuse channel. V-Ray doesn't read the alpha channel from PNG images, so it need to be separate.

        Thomas Thomassen — SketchUp Monkey & Coding addict
        List of my plugins and link to the CookieWare fund

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        • C Offline
          CurryPork
          last edited by

          How do you extract the alpha channel? I can't even find the PNG file from these trees. The 2D might be possible with Photoshop, but how would you extract from the 3D tree?

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          • GaieusG Offline
            Gaieus
            last edited by

            How did you get these trees? What the images used in them is needed is a clip map (if you can get the original png files, you can create these clips easily in PS).

            Gai...

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            • C Offline
              CurryPork
              last edited by

              Here are the trees. I got them either from here, the internet or the warehouse. But my point is how can you extract the PNG or the alpha channel from these sketchup files.


              2D tree


              3D tree

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              • thomthomT Offline
                thomthom
                last edited by

                Right click the material in the SU material editor, choose "Extract Texture Image". Save the file to disk and open in your image editor of choice to extract the alpha channel.

                Thomas Thomassen — SketchUp Monkey & Coding addict
                List of my plugins and link to the CookieWare fund

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                • C Offline
                  CurryPork
                  last edited by

                  Thanks Thom, I tried right clicking everywhere and cannot find that feature.


                  where.jpg

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                  • thomthomT Offline
                    thomthom
                    last edited by

                    Sorry. Be in the list of materials. Not in edit mode. (The "Select" tab next to "Edit")

                    Thomas Thomassen — SketchUp Monkey & Coding addict
                    List of my plugins and link to the CookieWare fund

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                    • C Offline
                      CurryPork
                      last edited by

                      Thanks Thom. I learned something new.

                      I got the alpha channel out of the tree now. Do you know how to make it work in Vray?

                      I assign a PNG as a bitmap in the COLOR slot in DIFFUSE and the alpha layer as a bitmap in the TRANSPARENCY slot in the DIFFUSE. But when I render in Vray it's not working... any suggestion?

                      Thanks

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                      • C Offline
                        CurryPork
                        last edited by

                        OK, I got it to work... thanks.

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                        • C Offline
                          chango70
                          last edited by

                          So how did you get it to work?

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                          • C Offline
                            CurryPork
                            last edited by

                            I have it working for the 2D tree and this works for the 3D tree as well. So, just extract the alpha channel from the original texture as Thom described.

                            In VRAY, apply the original texture in the Color slot and the alpha in the transparent slot. Render and this solves it.

                            Thanks Thom.


                            palm.jpg


                            coconut_test3_clean_green_alpha.png

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                            • C Offline
                              chango70
                              last edited by

                              Thx I just tried it myself and it works.

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                              • D Offline
                                devran
                                last edited by

                                Hi Fellowcombatants listen!!! First You download the tree from warehouse... click on the component open it then rightclick and save the png. then open in Photoshop and rightclick on the icon in the layers menu and choose choose pixels... change to channels menu and create a alpha channel... this channel is saveable as a new picture... rightclick on the alpha channel and save as a new picture... thats all.... ( sorry for all non Photoshop users)... ciao devran

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                                • T Offline
                                  tvicari
                                  last edited by

                                  You guys rock . . thanks for the tips, works great I have been looking for this solution for a long time. Thanks for making an effort and sharing knowledge.

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                                  • J Offline
                                    jdcarling
                                    last edited by

                                    Hey all,

                                    I read this post and have figured out how to create the alpha channel in photoshop for a tree, but cannot find the location to insert the png properly in the material editor - diffuse - transparency. I clicked the lower case, then switched the left panel to TEXBITMAP but coudl not insert the alpha channel PNG anywhere... any tips.

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                                    • J Offline
                                      jdcarling
                                      last edited by

                                      Hey All,

                                      I read this post and have figured out how to create the alpha channel in photoshop for a tree, but cannot find the location to insert the png properly in the material editor - diffuse - transparency. I clicked the lower case, then switched the left panel to TEXBITMAP but coudl not insert the alpha channel PNG anywhere... any tips.

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                                      • thomthomT Offline
                                        thomthom
                                        last edited by

                                        In the Transparency slot of the diffuse layer - add a TexBitmp:
                                        vfsualpah.png

                                        Thomas Thomassen — SketchUp Monkey & Coding addict
                                        List of my plugins and link to the CookieWare fund

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                                        • kaluK Offline
                                          kalu
                                          last edited by

                                          Hi thomthom:

                                          I have this dilema, I read the post all perfect. I try to mimic the results and I want to know what I am doing wrong. I attach the tree and the images for the render. Please let me know what I am doing wrong. I use Sketchup Pro 8 and Vray 1.48.89. Some of the leaves show as a rectangular green. I have no Idea why.

                                          Here is the link to the 3D model of the tree:

                                          https://rcpt.yousendit.com/1023169415/e1236da1e739047eed35fa1248da71be

                                          Thank you!!!!


                                          EU03lef.png


                                          EU03lef-Alpha.png


                                          tree.jpg


                                          tree01.jpg


                                          difuse01.jpg


                                          difuse02.jpg


                                          difuse03.jpg

                                          THE ONLY DIFFERENCE BETWEEN FICTION AND REALITY IS WHEN FICTION HAS TO BE CREDIBLE

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                                          • thomthomT Offline
                                            thomthom
                                            last edited by

                                            That's because you didn't map the backside of the faces. You can even see that in SketchUp.

                                            I'm guessing you imported this from another 3d format?
                                            Because of that you lost the backside information. Many other 3d apps doesn't display anything on the backside of faces. You have to explicitly enable it.

                                            To quickly transfer UV mapping from one side to another, use this plugin: http://forums.sketchucation.com/viewtopic.php?f=323&t=18992&p=155759#p155759

                                            Thomas Thomassen — SketchUp Monkey & Coding addict
                                            List of my plugins and link to the CookieWare fund

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