Baking a normal map

The file size of a 3D scan can be large. It can be reduced by removing surface details and faking them instead. A normal map is similar to a texture map, but instead of being rendered in color, it is interpreted by the render engine as surface details that catch the light or cast shadows.

Import the 3D file, scale, orient and set origin as needed. After scaling, apply scale (shortcut: ctrl + a > Scale).
Perform a general 3D scan cleanup if necessary.
Save the blender project as the high-resolution version. For example: scallop_hires.blend.
Save the same file, but name it as the lowres version. For example: scallop_lowres.blend.
Add the remesh modifier
- Set the mode to smooth.
- Set the Octree Depth to 8 and lower the Scale until you find a good spot between preserving the general shape and vertex count. Depending on the complexity of the object you might need to experiment with a different Octree depth.
- Apply the modifier.

Reducing the file size of the mesh by remeshing the object.

In edit mode, recalculate normals. Mesh > Normals > Recalculate Outside (shortcut: shift + n).

A normal map is essentially an image texture wrapped around a 3D model. Images are flat, so we need to define how we will flatten the 3D object in order to create a reference where the texture will go. Look at the model and find lines where we can cut the model in order to flatten it without too much distortion.

Since the shell is a simple shape, I can make a single cut that separates both halves of the shell. If you have a more complex shape, more cuts can be made.\\Hint: select the shortest path between vertices with ctrl + left mouse button.
Mark the current selection as a seam. Edge > Mark Seam (shortcut: ctrl + e)

Marking the current selection as a seam.