Surface Distance

The Surface Distance tool analyzes the Euclidean distance from every point on a surface to a specified reference point. The results are visualized as a color map and presented with comprehensive statistics, enabling distance-based surface analysis and measurement.

Overview

Distance analysis calculates the straight-line distance from each surface vertex to a reference point in 3D space. This creates a distance map that reveals:

• Radial relationships: How far surface regions are from a center point
• Proximity analysis: Identifying nearest and farthest regions
• Geometric relationships: Understanding spatial distribution around a reference
• Measurement verification: Checking distances against specifications

The tool provides both visual feedback through color mapping and numerical statistics for quantitative analysis.

Accessing the Tool

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

Reference Point Configuration

The reference point defines the origin from which all distances are measured:

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

Setting the Reference Point

You can set the reference point by:

1. Direct entry: Type coordinates into the X, Y, Z fields
2. Interactive picking: Enable Pick point on surface to update distances and click on the surface

Interactive picking is particularly useful for measuring distances from a specific surface location rather than an arbitrary point in space.

Statistics

The Statistics panel displays calculated distance metrics:

Metric	Description
Minimum	Shortest distance to the reference point
Maximum	Longest distance to the reference point
Range	Difference between maximum and minimum distances
Mean	Average distance across all points
Standard deviation	Measure of distance variability

These statistics provide a quantitative summary of the spatial relationship between the surface and the reference point.

Visualization Options

Range Adjustment

The range slider controls the color mapping limits:

• Lower bound: Distances below this value appear as the minimum color
• Upper bound: Distances above this value appear as the maximum color

Adjusting the range allows you to:

• Focus on a specific distance range of interest
• Increase color contrast for detailed analysis
• Highlight regions at particular distances

Show Max Distance

Enable Show max. distance to display a marker at the point farthest from the reference point. This helps identify the most distant location on the surface.

Show Min Distance

Enable Show min. distance to display a marker at the point closest to the reference point. This helps identify the nearest location on the surface.

Pick Point on Surface

Enable Pick point on surface to update distances to interactively set the reference point. When active, clicking on the surface:

1. Sets the clicked location as the new reference point
2. Automatically recalculates all distances
3. Updates the visualization and statistics

This mode is useful for exploring distance relationships from different reference locations.

Actions

Update

Click Update to recalculate the distance analysis with current settings. Use this after modifying the reference point coordinates manually.

Export

Click Export... to save the calculated distance data to a file. This exports distance values for all surface points, suitable for:

• External analysis software
• Documentation and reporting
• Further data processing

Copy to Measurements

Click Copy to Measurements to copy the visible distance measurements (min/max markers and values) to the Measurements panel for persistent reference.

Practical Applications

Sphericity Analysis

To assess how well a surface approximates a sphere:

1. Set the reference point at the expected sphere center
2. Calculate distances
3. Review the range (max - min) and standard deviation
4. Small values indicate good sphericity; large values indicate deviation

Radial Tolerance Verification

For verifying radial dimensions:

1. Position the reference point at the center axis
2. Calculate distances
3. Compare min/max distances against nominal radius
4. Adjust visualization range to tolerance limits for visual inspection

Proximity Mapping

To understand surface proximity to a critical point:

1. Set the reference point at the location of interest
2. Calculate distances
3. Use the color map to identify close and distant regions
4. Enable min/max markers to locate extremes

Feature Location

To find specific geometric features:

1. Calculate distances from a known reference
2. Enable pick mode to query specific locations
3. Use statistics to characterize feature positions
4. Export data for detailed analysis

Technical Considerations

Distance Calculation

The Euclidean distance $d$ from point $\mathbf{p}$ to reference point $\mathbf{r}$ is:

$$d = \|\mathbf{p} - \mathbf{r}\| = \sqrt{(p_x - r_x)^2 + (p_y - r_y)^2 + (p_z - r_z)^2}$$

All distances are positive (unsigned) values representing absolute distance regardless of direction.

Coordinate System

Distances are calculated in the global coordinate system using the surface's current world position. If the surface has been transformed, distances reflect its current location.

Vertex-Based Calculation

Distances are calculated at each vertex. For surfaces with large triangles, the actual closest point to the reference might be on a triangle face rather than at a vertex. For high precision requirements, consider remeshing to add more vertices.

Performance

Distance calculation is computationally efficient (linear in vertex count) and should complete quickly for most meshes. Very large meshes (millions of vertices) may take a few seconds.

Use Case Examples

Example 1: Checking Hole Concentricity

1. Position reference point at the nominal hole center
2. Calculate distances to the hole edge surface
3. If the hole is perfectly centered, all distances should be equal (the radius)
4. Range value indicates concentricity error

Example 2: Surface Deviation from Center

1. Calculate the surface centroid (average of all points)
2. Set this as the reference point
3. Calculate distances
4. The distribution shows how far points vary from the center

Example 3: Clearance Analysis

1. Set reference point at a critical location (e.g., insertion point)
2. Calculate distances
3. Minimum distance indicates closest approach
4. Verify minimum meets clearance requirements

Common Issues and Solutions

Issue	Likely Cause	Solution
All points same color	Reference point very far away	Move reference closer to surface
Very large distances	Reference point outside expected range	Verify reference point coordinates
Results not updating	Manual entry without Update	Click Update after changing coordinates
No color gradient	Range too wide	Adjust range slider to actual data range
Markers not visible	Show options disabled	Enable Show max/min distance checkboxes