Shortest Path

The Shortest Path tool calculates the geodesic (surface-following) shortest path between two points on a surface mesh. Unlike straight-line distance, this path follows the surface contours, providing accurate measurements for paths that must stay on the surface.

Overview

Geodesic distance represents the shortest path that can be traveled while remaining on the surface—like measuring distance along the skin of an object rather than through it. This type of measurement is essential for:

• Surface measurements: Accurate distances along curved surfaces
• Path planning: Routing along surface geometry
• Medical applications: Anatomical measurements following tissue surfaces
• Manufacturing: Cable routing, seam planning, surface coverage

The tool calculates the path using mesh connectivity and displays both the path visualization and the total distance.

Accessing the Tool

Navigate to the Surface ribbon tab and locate Shortest Path in the Analyze section. Select a surface object before activating the tool.

Defining Path Endpoints

The shortest path is calculated between two points on the surface:

Start Point

The starting point of the path, defined by:

Parameter	Description
X-position	X-coordinate of start point (mm)
Y-position	Y-coordinate of start point (mm)
Z-position	Z-coordinate of start point (mm)

Click Pick start point to interactively select the start location by clicking on the surface.

End Point

The ending point of the path, defined by:

Parameter	Description
X-position	X-coordinate of end point (mm)
Y-position	Y-coordinate of end point (mm)
Z-position	Z-coordinate of end point (mm)

Click Pick end point to interactively select the end location by clicking on the surface.

Interactive Point Selection

The interactive picking workflow is recommended:

1. Click Pick start point
2. Click on the surface at the desired starting location
3. The coordinates update automatically
4. Click Pick end point
5. Click on the surface at the desired ending location
6. The path is calculated and displayed immediately

Shortest Path Measurements

The measurement table displays path information:

Metric	Description
Path length	Total geodesic distance along the surface (mm)
Straight-line distance	Direct distance between endpoints (mm)
Number of segments	Path segments in the calculated route

The difference between path length and straight-line distance indicates how much the surface curvature affects the actual travel distance.

Visualization Options

Show Annotations

Enable Show annotations to display measurement labels in the 3D view, including:

• Start and end point markers
• Path length annotation
• Distance labels

Show Path Nodes

Enable Show path nodes to display the intermediate vertices along the calculated path. This helps visualize:

• The exact route the path takes
• How the path navigates mesh topology
• Potential areas where path could be optimized

Actions

Export

Click Export... to save the path data to a file, including:

• Start and end coordinates
• Path length
• Individual path node coordinates

This data can be used for external analysis, documentation, or manufacturing instructions.

Copy to Measurements

Click Copy to Measurements to add the current path measurement to the Measurements panel for persistent reference alongside other project measurements.

Practical Applications

Anatomical Measurements

For medical applications requiring measurements along anatomical surfaces:

1. Select the anatomical surface model
2. Pick start point at one anatomical landmark
3. Pick end point at another landmark
4. The geodesic distance follows the tissue surface
5. Export for clinical documentation

Cable/Wire Routing

For planning cable paths along enclosures or equipment:

1. Select the enclosure surface
2. Define start point at cable entry
3. Define end point at destination
4. The path shows the shortest surface-following route
5. Use path nodes for routing guidance

Surface Coverage Planning

For coating, painting, or inspection planning:

1. Define start and end points of coverage path
2. Calculate multiple paths to understand coverage distances
3. Export path data for planning documentation

Quality Inspection

For measuring surface features:

1. Pick points at feature boundaries
2. Measure geodesic distance along the feature
3. Compare against specifications
4. Document with Copy to Measurements

Technical Considerations

Algorithm

The shortest path is calculated using Dijkstra's algorithm on the mesh graph, where:

• Vertices are graph nodes
• Edge lengths are graph weights
• The path follows mesh edges

The result is the shortest path through mesh connectivity, which closely approximates the true geodesic for well-tessellated meshes.

Mesh Resolution Impact

Path accuracy depends on mesh resolution:

• Fine meshes: More accurate paths with more routing options
• Coarse meshes: Paths constrained to fewer edges, potentially longer than optimal
• Highly curved regions: Benefit from higher resolution

For precision measurements on curved surfaces, consider remeshing to increase vertex density.

Path Topology

The calculated path:

• Always follows mesh edges (vertex to vertex)
• Cannot cut across triangle faces
• Is guaranteed to be the shortest possible path through the mesh graph
• May differ slightly from the true continuous geodesic

Multiple Shells

If the surface contains multiple disconnected shells, paths can only be calculated within a single shell. Start and end points must be on the same connected component.

Performance

Path calculation uses efficient graph algorithms:

• Small meshes (< 100K vertices): Nearly instantaneous
• Medium meshes (100K - 1M vertices): A few seconds
• Large meshes (> 1M vertices): May take longer

Path calculation is performed once when both endpoints are defined.

Comparison: Geodesic vs. Straight-Line Distance

Aspect	Geodesic (Shortest Path)	Straight-Line (Euclidean)
Path constraint	Follows surface	Through space
Typical length	Longer	Shorter or equal
Use case	Surface measurements	Direct distance
Physical meaning	Travel distance on surface	Line-of-sight distance

The ratio of geodesic to straight-line distance indicates surface curvature between the points. A ratio close to 1.0 indicates a relatively flat path; larger ratios indicate significant curvature or obstacles.

Common Issues and Solutions

Issue	Likely Cause	Solution
No path calculated	Points on different shells	Ensure both points are on the same connected surface
Path looks jagged	Coarse mesh	Remesh for finer resolution
Path very long	Mesh has obstacles or gaps	Check mesh topology; points may be on opposite sides
Picking not working	Wrong tool mode	Click Pick start/end point button first
Path not visible	Visualization disabled	Enable Show annotations