Image Based Surface Modeling in Sketchup

Image Based Surface Modelerimg bas

Plugin by: OCALI Inc.
Categories: photometry
Availability: Trial
Instructions for Downloading and Installing
Click here to Download This Plugin.
Watch complete Installing instructions click here

How to use Image Based Surface Modeler

Image based surface modeler is a Tgi3D tool that help modelers create free form surfaces that match the images on photomatch-pages. The basic image based surface modeling process consists of the following steps:

  1. Create a mesh on one of the photomatch pages facing the surface you want to draw at a right angle. Do not bother about the 3D shape of the mesh, just assume you are creating a 2D mesh over the photograph on the page.
  2. Lock the mesh on the current view using the Tgi3D “lock vertices” command.
  3. Switch to another photograph facing the surface from a different angle.
  4. Choose the Tgi3D image based surface modeler tool, which will pop-up a new toolbar.
  5. Use one the command buttons on the toolbar for shaping the surface.
  6. Check the markers appearing on the mesh that you created. Pure green plus signs indicate successfully matched triangles on the mesh, while red minus signs indicate bad matches. The ones without any signs are neutral. You can also check the quality of the surface from other views. Do not expect to get a good match all over the surface.
  7. Depending on your evaluation in step 6, you can go to step 5 to issue another match command or stop if you are satisfied with the result. If your previous command resulted in a very low quality surface you can issue an undo command and go to step 5 to issue another one.

Tools

Initial Estimate Initial Estimate

Initial estimate is used for reshaping surfaces that are far away from the target surface. You can determine such surfaces by checking the markers on it and its appearance on a view other than the locked one.

If the surface

  • have all negative markers on it
  • appears off the target surface on any of the available images
  • is not connected to another surface that is already shaped correctly

you may want to use initial estimate command.

Initial estimate command corresponds to a long range search targeting multiple surfaces.

Single-Segment SurfaceSingle-Segment Surface

Single-segment surface is a smooth surface that you can unfurl using a single sheet of a soft material without any tears; otherwise the surface is called a multi-segment surface. Single-segment surfaces do not contain any creases or breaks. A ball or the torso of human body can be considered as asingle-segment surface, while the whole surface of a cube is a multi-segment surface due to vertical creases at the edges of the cube. The total visible surface of an object and another object partially occluding it should also be considered as a multi-segment surface due to the breaks, which are discontinuities in space. It is impossible to unfurl two different objects with a single sheet.

Use the single-segment surface command for a surface

  • that does not contain very sharp creases,
  • that does not contains breaks as in the case of multiple objects.

Single-segment surface command corresponds to a medium range search targeting a single smooth surface.

Multi-Segment Surface Multi-Segment Surface

Single-segment surface is a smooth surface that you can unfurl using a single sheet of a soft material without any tears; otherwise the surface is called a multi-segment surface. Single-segment surfaces do not contain any creases of breaks. A ball or the torso of human body can be considered as asingle-segment surface, while the whole surface of a cube is a multi-segment surface due to vertical creases at the edges of the cube. The total visible surface of an object and another object partially occluding it should also be considered as a multi-segment surface due to the breaks, which are discontinuities in space. It is impossible to unfurl two different objects with a single sheet.

Use the muti-segment surface command for a surface

  • that contains very sharp creases,
  • that contains breaks as in the case of multiple objects.

Multi-segment surface command corresponds to a medium range search targeting multiple smooth surfaces

Refine Estimate Refine Estimate

Refine estimate command improves the quality of matching regions on the mesh. It can be used to after obtaining a fairly good estimate of the target surface. It corresponds to a narrow range search to let the mesh adapt to the fine details of the target surface.

Upsample Mesh Upsample Mesh

Upsampling increases the resolution of the mesh. It is best to start image-based modeling with low-resolution meshes. Once you get a good estimate of the surface at a low resolution use the upsample mesh and refine estimate command to obtain a more detailed mesh to represent the target surface

Flip if Necessary Flip if necessary

This command changes the topology of the mesh to capture sharp discontinuities in the surface. The edges are flipped as in the “Flip Edge” tool of the “Sandbox Plugin” based on the image matching quality.

Leave a Reply

Your email address will not be published. Required fields are marked *