I am using the following code to show a drawing in a display box ____________________________________________________________________________ model = DxfReader.ReadDxf(filename); gdiGraphics3D = new GDIGraphics3D(GraphicsConfig.Default, BackColor); gdiGraphics3D.CreateDrawables(model); bounds = new Bounds3D(); bounds2 = bounds; gdiGraphics3D.BoundingBox(bounds, modelTransform); CalculateTo2DTransform(); dxf_loaded = true;  dxf.Invalidate();  dxf.Focus(); private Matrix4D CalculateTo2DTransform()     {       Matrix4D to2DTransform = Matrix4D.Identity;       if (bounds != null)       {         double halfHeight = dxf.ClientSize.Height / 2;         double halfWidth = dxf.ClientSize.Width / 2;         to2DTransform =           Transformation4D.Translation(translation) *           Transformation4D.Translation(halfHeight, halfWidth, 0) *           Transformation4D.Scaling(scaleFactor) *           Transformation4D.Translation(-halfHeight, -halfWidth, 0) *           DxfUtil.GetScaleTransform(             bounds.Corner1,             bounds.Corner2,             bounds.Center,             new Point3D(0d, ClientSize.Height, 0d),             new Point3D(ClientSize.Width, 0d, 0d),             new Point3D(ClientSize.Width / 2, ClientSize.Height / 2, 0d)           );       }       gdiGraphics3D.To2DTransform = to2DTransform * modelTransform;       screenpoint.X = 0;       screenpoint.Y = 0;       screenpoint.Z = 1;       tomodelspace = to2DTransform.GetInverse() * screenpoint;       lbl_topleft.Text = Convert.ToString((int)tomodelspace.X) + ' , ' + Convert.ToString((int)tomodelspace.Y);       int tms1x = (int)tomodelspace.X;       int tms1y = (int)tomodelspace.Y;       screenpoint.X = 480;       screenpoint.Y = 480;       screenpoint.Z = 1;       tomodelspace = to2DTransform.GetInverse() * screenpoint;       int tms2x = (int)tomodelspace.X;       int tms2y = (int)tomodelspace.Y;       storeX1 = Convert.ToString(tms1x);       storeX2 = Convert.ToString(tms2x);       storeY1 = Convert.ToString(tms1y);       storeY2 = Convert.ToString(tms2y);       lbl_bottomright.Text = Convert.ToString((int)tomodelspace.X) + ' , ' + Convert.ToString((int)tomodelspace.Y);       lbl_size.Text = Convert.ToString(tms2x - tms1x) + ' , ' + Convert.ToString(tms1y - tms2y);       return to2DTransform;     } +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Although the code appears to be identical the amount of an identical drawing shown in the output box (before any mouse scrolling or panning) is around 25% for one application, for a second application around 50%. Is there any way to force a displayed dxf to be shown to the extends in the middle of the vview box, if so how do I alter the above code to achive this. (Box size is 280 by 480 pixels) Regards   ______________________________________________________________________________

Found it - ;D new Point3D(0d, dxf.ClientSize.Height, 0d), new Point3D(dxf.ClientSize.Width, 0d, 0d), new Point3D(dxf.ClientSize.Width / 2, dxf.ClientSize.Height / 2, 0d) The ClientSize being used was that of the form (default) not the imagebox I was using to display. Changed the code as above and all is now spot on

Ah, great! 8) Seems you're getting the hang of using the 3D transformations! Wout