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    Alpha Channel, Trees, Vray - HELP

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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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                                          • kaluK Offline
                                            kalu
                                            last edited by

                                            Thank you ThomThom, aweomse your plugin, I have that problem when Import 3DS trees...

                                            This is the result:


                                            tree.jpg


                                            tree1.jpg

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

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