How do I know if I am infringing a patent?

Question

I am developing a 3D modeling application.

How can I know what is considered as part of the sketchup patent?

The extrude tool is obviously common to all 3D modeling softwares, that makes me think that what is patent is the ability to draw arbitrary 2D shapes on a 3D face, with automatic intersections computation and automatic triangulation.

However 3Ds max also has the "Cut tool" or the "Paint Connect tool" to draw lines and compute intersections on any face.

The only difference I see is that Sketchup 3Ds max does not support holes (polygon holes) on a face, and it does not provide any tool to draw directly a rectangle or circle on a face.

Can I make a rectangle tool (a rectangle is just a set of 4 lines)? Can I handle holes?

When I create a new modeling tool, how can I know it remains out of the Sketchup patent?

What do I risk by implementing those features? A fine? Obligation to remove my product from the US market? Obligation to remove some features?

Answer 1

How can I know what is considered as part of the Sketchup patent?

You obtain a copy of the granted patent and look at the claims. The claims define what is protected by the patent. What is disclosed in the description is largely irrelevant (except, potentially, for interpretation).

If the tool that you produce implements all the features of one of the claims, then you infringe that claim of the patent.

Once you consider the scope of the claims, you can look at whether you believe the claims are valid. If you can form a good argument that the claims are invalid based on solid prior art, you might decide that you can ignore the patent. However, you can never be sure until the patent is actually revoked.

What do I risk by implementing those features?

If you infringe the patent (by making, using, selling, offering to sell, or importing into the US the patented product (35 USC § 271), and you cannot invalidate the patent, you would be liable for "damages adequate to compensate for the infringement" (35 USC § 284). In effect, this is the lost revenue by the patent holder due to your action. This may be tripled where it can be shown that you willfully infringed, by knowing about the patent. You can also be injuncted from further infringement (35 USC § 283).