<HTML><BODY style="word-wrap: break-word; -khtml-nbsp-mode: space; -khtml-line-break: after-white-space; "><BR><DIV> <SPAN class="Apple-style-span" style="border-collapse: separate; border-spacing: 0px 0px; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; text-align: auto; -khtml-text-decorations-in-effect: none; text-indent: 0px; -apple-text-size-adjust: auto; text-transform: none; orphans: 2; white-space: normal; widows: 2; word-spacing: 0px; "><SPAN class="Apple-style-span" style="border-collapse: separate; border-spacing: 0px 0px; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; text-align: auto; -khtml-text-decorations-in-effect: none; text-indent: 0px; -apple-text-size-adjust: auto; text-transform: none; orphans: 2; white-space: normal; widows: 2; word-spacing: 0px; "><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">Hi,</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><BR class="khtml-block-placeholder"></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "> I am using vtk within our OpenGL/Qt legacy code for volume rendering using 2D texture mapping. vtkRenderWindow is made to use the existing GL window using SetWindowId(), and vtkInteractor is not used at all. Instead, I pass the current transform from the legacy code using SetUserTransform() to the volume. Now everything works fine except for the lighting. I do not create my own lights but just let vtk take care of it. However, it appears to be extremely sensitive to the diffuse level set in vtkVolumeProperty (diffuse: 0.005, specular: 0.7, ambient: 0.4, specular power: 50). I have played around with different values, and only this combination of mine gives somewhat reasonable lighting. </DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><BR class="khtml-block-placeholder"></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "> I currently use my own vtkCamera because we want it to have the same projection matrix as from the legacy code. However, if I let vtk create its own camera then the lighting problem goes away and I can take the diffuse value to 0.2 or higher and actually improve the appearance of the volume. Though of course, the view transformations are incorrect in that case. I am not sure what exactly is causing this behavior on introducing my own camera. First I suspected that vtk did not impose GL_NORMALIZE, but that does not seem to be the problem. Can somebody help me out with this?</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><BR class="khtml-block-placeholder"></DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">Thanks!</DIV><DIV style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">Amit</DIV></SPAN></SPAN></DIV><BR></BODY></HTML>