Mesh upsampler

[marrts]

The primary motivation for this was to fix an issue with the ROI selection mesh modifier in snp_tpp that would perform poorly with sparse meshes, but this felt better suited to go here.

This takes a single parameter (Max alllowed area) and continually subdivides all triangles greater than this area until all triangles on the mesh are the right size.

The mesh goes from this:

To this;

Resulting in a toolpath going from this:

To this:

[marip8]

This is not needed if you create this layout with this as the argument

Suggested change

layout->addLayout(form_layout);

[marip8]

Suggested change

	double max_area_;
	const double max_area_;

[marip8]

Suggested change

	midpoint.x = 0.5f * (v_start.x + v_end.x);
	midpoint.y = 0.5f * (v_start.y + v_end.y);
	midpoint.z = 0.5f * (v_start.z + v_end.z);
	midpoint.getVector3fMap() = 0.5f * (v_start.getVector3fMap() + v_end.getVector3fMap());

[marip8]

Trying to simplify just a little

Suggested change

	pcl::PointXYZ v0 = vertices[idx0];
	pcl::PointXYZ v1 = vertices[idx1];
	pcl::PointXYZ v2 = vertices[idx2];
	// Compute area of triangle
	Eigen::Vector3f p0(v0.x, v0.y, v0.z);
	Eigen::Vector3f p1(v1.x, v1.y, v1.z);
	Eigen::Vector3f p2(v2.x, v2.y, v2.z);
	float area = 0.5f * ((p1 - p0).cross(p2 - p0)).norm();
	pcl::PointXYZ v0 = vertices[idx0];
	pcl::PointXYZ v1 = vertices[idx1];
	pcl::PointXYZ v2 = vertices[idx2];
	// Compute area of triangle
	Eigen::Vector3f e1 = (v1.getArray3fMap() - v0.getArray3fMap());
	Eigen::Vector3f e2 = (v2.getArray3fMap() - v0.getArray3fMap());
	float area = 0.5f * (e1.cross(e2).norm();

[marip8]

Do you want to call this something a little more specific like AreaBasedUpsamplingMeshModifier? I could also see another implementation of this upsampler that looks at edge length rather than area which would need a differentiated class name

[marip8]

We could also make another instance of this based on PCL mesh subdivision using VTK

[marip8]

Let's move this to the source file; seems pretty specific to this class

[marip8]

This will remove all other extraneous data from the mesh (e.g., color, normals, curvature, etc.). It's probably worth looking a little more into preserving that information for the newly generated midpoints. It seems like it should be possible by adding the midpoints to the end of the vertex list and interpolating the extraneous data based on its two edge endpoints. Then you could use this function to cull the unreferenced vertices. You can also used functions like pcl::concatenate and pcl::concatenateFieldsto combine twopcl::PCLPointCloud` objects (i.e., the original mesh vertices and the newly added midpoints)