InStep Studio


Using the Bodies - Thicken (Solidify) option

Time to read: ~3 min

The Thicken option, defined by the parameters in the Options on the left-hand side of the main display, is primarily focused on generating a solid body from an original body that does not define a closed volume.

Thicken Button in Bodies Thicken

As mentioned on the Bodies - Tab page, the Thicken tool is somewhat unique within InStep in that it can generate new data from existing surfaces by offsetting and connecting faces based on a few simple rules.

The image below shows a typical case where the thicken option is applicable:

Image of shell body
Shell Body

This body is the result of a local 3D scan of a special shape. Though it could be exported to a STEP file and used in the target application as a sheet body, that is not always the case with applications that require solid body data.
For this shape, the most appropriate option is to thicken the body by using the default options provided in the Options panel (under its Thicken Tab):

The Method drop-down options include
  • Local
  • Uniform
  • To Plane
Local means that at each vertex/point, the normal resulting from the normalized average of its surrounding faces is taken and then multiplied by the Factor provided below. This is generally considered the default (and best) option as it accounts for local warping in the surface. It generates a smaller offset where there are many surfaces that are strongly bent and thus avoids expanding the surface to intersect others nearby.
Uniform approaches the offset similar but, at each location, computes the unit length of the averaged normal and then multiplies this by the provided factor to effectively get a original-to-new location distance that is the same everywhere.
To Plane offers a different approach in that all newly generated points are projected onto a plane (surface). In general, this will not lead to a useful shape except for cases where the surface is more or less flat or at the least does not have regions that fold over the projection direction. this can be useful for cases where the ultimate use is to generate a solid block for machining or similar processes where the back side is simply considered material stock. It further also helps is reducing the size as all projected faces can be combined into a single, planar polygon.
Depending on the 'Method' selected, the option will provide the local Factor (the multiplier), the uniform Distance or the definition of the plane to project to (given either as a point and normal direction, three points or a coordinate plane such as the X-Y plane)
Use Quads
This option allows the sides (where the edges are defining the boundary of the shell surface) to be generated as single Quadrilateral shapes rather than two triangles. This can reduce the size of the final STEP file but may introduce additional issues when other tasks are performed that require triangles.

Image of thickened Shell body
Shell Body thickened into a Solid

The result for the default parameters shows that the new surfaces very closely match the original data with a thin offset applied and boundaries closed.


The Thicken tool only operates on Triangular and, to some extent, Quadrilateral facets. For other shapes, the inflation process is not as straight forward and thus best reserved for other tools. It is possible to perform tasks on the inflated/thickened surfaces though, so performing any required processes afterwards is an option. If other processes are intended (such as perhaps converting to NURBS from the Rev-Eng: Surfacing tool), then keeping the data as triangles is recommended.