SLS Scanning Workflow

Scan (Acquire Data)

Once the object and environment have been prepared, the scanner can be set up and scanning can begin.

During the scanning process multiple light patters are rapidly projected onto the object being scanned. Single or multiple cameras are then used to capture the light patterns' distortion across the object or environment.

Scanning will be covered further in the practical demonstration.

After a scan session has been completed, data can be processed to construct a digital model

Process Scan Data

Clean

The first step in this process is to "clean" the individual scans. During this process all unwanted data such as background information, propping devices, outliers, misaligned frames and poor quality scans can be removed.

Align

Now that scan data has been cleaned, an alignment can be performed. During the alignment process data from multiple scans is transformed into a single coordinate system.

In most cases the alignment process is automated using alignment & registration algorithms.

If scans do not share many key features they may need to be aligned manually. This can be done by visually selecting a collection of matching points between two scans. Scanning software will then attempt to align the scans based on these new key features (datums). This method is referred to as pair wise registration

If there are sections of the object missing after the alignment process, further scans will be required. It is best to re-orient the object and complete either;

• a full 360⁰ scan (Handheld Scanning method)

OR

• a number of single scans focussing on the missing faces. (Mounted/Fixed Scanning Method)

Generally, a model will require at least 2 full 360⁰ scans to ensure the sides, base, and top of an object are fully captured.

Fuse

Once scan frames have been aligned, scans can be fused together to create a 3D model. During this process the aligned scans are effectively melted and solidified into a single mesh. This mesh may be open OR watertight depending on your fusion settings

Export

Once fused, scans can be exported from scanning software by exporting the meshes.

dFab recommends always saving a copy of the scanning project & the fused scan in multiple formats

.stl

Stereolithography file format.

Suitable For 3D Printing

Geometry Only

.wrl

VRML file - Virtual Reality Modelling Language

Geometry + Texture

Texture data stored in accompanying files

.obj

Wavefront OBJ file format

Geometry + Texture

Texture data stored in accompanying files

.ply

Stanford polygon file format

Geometry + Texture

Texture data stored in accompanying files

Exporting is not the final step! Even if an object has been scanned at several times it may not be perfect. Touch ups can be made within the scanning software or in a mesh editing software such as Mesh Mixer, Rhino.