# Surface Measurements & Model Comparison in 3D Slicer

**URL:** <https://discourse.slicer.org/t/surface-measurements-model-comparison-in-3d-slicer/44264>\
**Category:** Support\
**Created:** [August 29, 2025, 5:05pm UTC](https://discourse.slicer.org/t/surface-measurements-model-comparison-in-3d-slicer/44264 "2025-08-29T17:05:10Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Faisal\_Alshaikh](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/faisal_alshaikh/32/78527_2.png) [@Faisal\_Alshaikh](https://discourse.slicer.org/u/Faisal_Alshaikh)\
**Post date:** [August 29, 2025, 5:05pm UTC](https://discourse.slicer.org/t/surface-measurements-model-comparison-in-3d-slicer/44264/1 "2025-08-29T17:05:11Z")

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Hello everyone,

I am currently testing 3D Slicer with **surface models exported from the Vectra H2 system (.obj format with texture)**. The models import and display correctly in the 3D view, but I could not find direct options for:

- **surface-area measurement** of freely selected regions (e.g. around the eyes),

- **automatic difference calculation / distance mapping** between two surface models (e.g. before vs. after treatment).

So far, model comparison seems limited to manual alignment using transforms. I could not find an automatic registration tool or quantitative difference mapping (heatmap) for OBJ surface meshes.

My questions are:

- Does 3D Slicer support surface-area measurements for OBJ meshes?

- Is there a way to perform automatic comparison (registration + difference/heatmap) between two surface models?

- Are there modules, extensions, or Python scripts that can be used for this workflow?

Any advice, references, or example workflows would be greatly appreciated.

Thank you!

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<div class="post-metadata">

**Author:** ![lassoan](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/lassoan/32/13_2.png) [@lassoan](https://discourse.slicer.org/u/lassoan)\
**Post date:** [August 29, 2025, 5:12pm UTC](https://discourse.slicer.org/t/surface-measurements-model-comparison-in-3d-slicer/44264/2 "2025-08-29T17:12:59Z")

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You can see the surface area of a model in `Models` module → `Information` section.

If you are interested in a specific region then you can use `Dynamic modeler` module to extract a region of the model. There are several tool to choose from: `Plane cut` defines a region by a one or more planes, `Curve cut` allows you to specify a surface region by a closed curve, `Boundary cut` allows using several node types (curves, planes, etc), `ROI cut` works for markup ROI boxes, `Select by points` can select a region using Euclidean or geodesic distance from points.

You can compute distances between surfaces using `ModelToModelDistance` extension.

`ModelToModelDistance` computes distances and stores them as point scalars in the model, which then you can use for computing statistics, crop the model, etc. - using a few Python commands that you can run directly in Slicer’s Python console.