Tuesday, December 9, 2014

Another update in Autodesk Memento - comparing 3D models

One of the fastest growing Autodesk application is the tool for processing large 3D mesh models - Autodesk Memento. It is an important tool for 3D reality-capture from photos, 3D point-cloud scanning or handheld scanners - converting the acquired data into 3D models for CAD and BIM software. Today released version of Memento (V1.0.12.1; expires March 31,2015) brings a couple of important new features. You can export AVI videos with presentations of the model in multiple resolutions. 3D navigation in the model was simplified by using the spherical orbit gizmo and by assigning coordinate systems to the processed model. You can export OBJ files without textures or with re-baked textures. There is an enhanced support for Artec 3D scanners.

But probably the most interesting new feature is the difference analysis between two 3D meshes. You can easily perform a comparison of differences between two mesh models. The results are presented as a colored hypsometry enhancing positive and negative changes of the model geometry - comparing two different files or an old and a new version of the same model. So you can easily compare e.g. photographed and generated 3D models of the same scene after some time (e.g. plant growing, terrain erosion), compare the theoretical (CAD-based) and the real shape of a manufactured and scanned 3D part, find changes in geometry between two versions of a 3D assembly from a CAD software (outer shape only, a mesh).

In the sample below, a doggie-toy model (generated in Memento from a photographed scene) was modified to a new version by using the "push" and "pull" smoothing tool on the dog's neck and back leg. Subsequently, the function Analyze > Analyze the difference was used to compare the loaded model with its original untouched version (.RCM file on disk). The dialog "Difference analysis" allows to set the display scale for the difference sizes, plus the "neutral area", where small differences are ignored. The result then clearly indicates areas where the model shape was changed using the "3D brush" (by adding and subtracting mass).

The original model:

Edit by smoothing:

Result of the comparison:

See Project Memento on Autodesk Labs.

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