1.1. What you will need

The object

3DSOM Pro works well with many kinds of object but may have trouble modelling transparent objects (e.g. non-coloured glass), extremely complicated shapes (e.g. a hairbrush), mirrored objects and objects with deep holes (e.g. a cup).

The mat

The 3DSOM Pro calibration mat is a flat sheet of paper with special markings which 3DSOM Pro system uses to determine the angle from which each photograph was taken.

The 3DSOM Pro   calibration mat can be printed from within the 3DSOM Pro software, using the Print mat... button on the Main Window toolbar.

The mat must be perfectly flat and it is recommended that the mat be firmly stuck down onto a solid flat surface.

The mat is typically printed on an A4 sheet of white paper but this will of course depend on the size of the object being modelled. You can adjust the size and paper by choosing File > Page Setup... menu item. All the important mat features lie within the outer circle (see Figure 1.1.2).

TIP:	If you trim the mat, then make sure it is lying flat (not curling up at the edges), and if necessary, stick it to a flat sheet of something rigid such as cardboard.

The stand

The stand is useful for raising the object away from the markings on the mat and reducing shadows cast onto the mat. It also helps you to completely surround the object with the backdrop.

The stand should ideally be:

• Narrower than the object (to avoid making the bottom part of the object appear in shadow).
• Opaque and the same colour as the backdrop (to help automatic masking).
• Able to support the object.
• Stable enough to allow rotation of the scene. (stick it to the mat if necessary).

TIP:	If the stand and\or object is too large and naturally overlaps the markings on the calibration mat, then you will need to use a larger size mat.

The backdrop

The backdrop is a matte plain coloured sheet, which provides a consistent background behind the object. This allows 3DSOM Pro to determine which parts of the image correspond to the object. If you are unable to use a suitable backdrop you will have to spend more time manually masking the photographs (see Masking the images).

The backdrop should...

• ...be plain matte coloured or white. Choose a colour that contrasts with the object. Light colours work better than dark colours.
• ...be smooth surfaced and free from marks or creases.
• ...surround the object.

3DSOM Pro assumes that any features it finds as it goes around the outline belong to the object. If 3DSOM Pro is unable to do this automatically you will need to mask the images by hand using the masking tools.

TIP:	Note if you choose a strong colour then don't use too large a backdrop as the colour may be reflected onto the sides of the object.