Houdini 11 Nodes Surface nodes

Converts geometry from one geometry type to another.

## Using Convert

1. Select the primitive to convert.

2. Click the Convert tool on the Model tab.

3. Choose the geometry type in the Convert To drop-down menu on the operation controls toolbar or the parameter editor.

## Face to Surface Conversion

When converting from a set of polygons to a mesh, a single mesh will result only if:

• more than one polygon is in the input, and

• each polygon has exactly four points, and

• the polygons are arranged as n rows by n columns

• the polygons share coincident points (see Facet OP)

Otherwise, each polygon is converted individually into a mesh. In fact, any individual face can be converted to any surface. This is accomplished by cutting the face into three or four adjacent sections, and then creating a patch from them.

## Parameters

 Group Subset of primitives to convert. From Type Which geometry types will be converted. Convert To What the geometry will be converted to. Connectivity Method of surface construction.

### Level of Detail

 Overview Use a floating point level of detail to determine conversion resolution. A value of 1 will divide once per voxel. U Point density in U direction. V Point density in V direction. Trim-Curve Point density for the trim curves.

### Divisions

 Overview Exact number of points to be computed within each span. U Point count in U direction. V Point count in V direction. Trim-Curve Point count for the trim curves.
 U Order Spline order of curves & surfaces in U. V Order Spline order of curves & surfaces in V. Paste Coordinates Evaluate base or feature surface for position. Paste Attributes Evaluate base or feature surface for attributes. Preserve Original Retains original geometry along with converted geometry. Interpolate Through Hulls Splines will preserve the shape of the geometry they are converted from. Otherwise, points in the geometry are used as points in the hull. Volume Offset When converting volumes to polygons, this is the value of the isosurface that will be extracted. 0 works for Signed Distance Fields. 0.5 might work better for a fog volume. Note: For faster conversion of volumes, consider using the specialized Convert volume.

## Examples

 ConvToTrimSurface Load | Launch `.../examples/nodes/sop/convert/ConvToTrimSurface.otl`This example shows how to create a trimmed NURBS or Bezier surface using the Convert SOP. There are four examples contained that compare how a trimmed surface handles a texture. Grid Surface a simple texture map on a grid. Trimmed Circle Using the Trim SOP the conventional way of creating a trimmed surface using a Project SOP and a Trim SOP. Trimmed Circle Using the Convert SOP creates a trimmed surface using a Convert SOP. NURBS Surface Using the Convert SOP shows how a texture is parametrized over a surface that is not trimmed. To get a better sense of the parameterization of the texture, turn on points and toggle between wireframe and shaded modes. ConvertBasic Load | Launch `.../examples/nodes/sop/convert/ConvertBasic.cmd`This example shows the various ways in which the Convert SOP converts geometry types using a simple sphere. A chart is used for this demonstration. The left column of the chart describes the original geometry type to convert from. The top row of the chart describes the geometry type to convert to. All Sphere SOPs and Convert SOPs in this demonstration use their default values to better visualize the differences. CurveToPrimCircle Load | Launch `.../examples/nodes/sop/convert/CurveToPrimCircle.otl`This example is a simple demonstration on how to convert a curve into a primitive circle. To convert a NURBS or Bezier closed curve to a primitive circle, it must first be converted to a polygon. Once converted to a closed polygon curve, you can convert the curve to a primitive circle. PasteConvertVariations Load | Launch `.../examples/nodes/sop/convert/PasteConvertVariations.otl`This example deomonstrates the various ways in which to convert pasted geometries into a single surface. The parameters, Paste Coordinates and Paste Attributes, tell the Convert SOP how to handle displacements and attributes. There are four objects, each containing the same SOP network. The only difference is in the Convert SOP, which contains differences in Paste Coordinates and Paste Attributes. In the SOP networks, there are two grid surfaces that have been deformed using the Edit SOP. Each grid has a Color attribute added, using a Point SOP. The red grid, or the Feature Surface, is pasted onto the blue grid, or the Base Surface. The parameters in the Convert SOP in each network distinguishes the way that the Feature Surface is pasted onto the Base Surface. PastedHeirarchy Load | Launch `.../examples/nodes/sop/convert/PastedHeirarchy.otl`This example shows how you can convert two pasted geometries into a single surface. In order for the Paste SOP to work, both geometries must be NURBS or Bezier surfaces. The first geometry is a NURBS grid that has been deformed using the Clay SOP. The second geometry is a NURBS circle, which is converted into a NURBS surface using a Convert SOP. The deformed grid is pasted onto the NURBS circle parametrically using the Paste SOP. However, in order to make both geometries into a single surface, a Convert SOP is necessary. To convert the pasted surfaces into a single surface, they need to be converted to a mesh or a polygon first. They can then be converted to a NURBS or Bezier surface using another Convert SOP. Potatochip Load | Launch `.../examples/nodes/sop/convert/Potatochip.otl`This example demonstrates how to convert a closed curve into a surface using the Convert SOP. There are two versions contained in this example. One curve has been successfully converted to a surface, the other has not because of the concave shape of the original curve. View in shaded mode to get a better sense of this.