When is a freemium business model the best option?

The freemium model works well in situations where you are trying to create significant scale of users or clients in a short period of time either for commercial purposes or to test your technologies and processes.

In terms of this business method over traditional licensing, I view this as licensing with a zero price. You'll still need to ensure that your "freemium" agreement has the same protections as would an agreement with a cash or cash-like fee.

1) Whenever a product/service becomes "cheap" (zero the lower bound) value migrates to the edge. For example when IBM produced low-cost assembly of components, the value migrated to hardware (x86 Intel) and higher end applications (Office suite). Ditto you need to look at your product and figure out if hardware is your revenue model or PaaS. If you are adapting stereo compositions (I saw similar tech in US uni) to figure out the 3d shape, then you are driving value towards phone cameras which you have qualified your tech (so perhaps extract a fee from Samsung or HTC) and driving users towards your website (cf pinterest for upgrading photos).

2) Product-market fit ... who is the customer? Freemium works for a prosumer market, where you want to convert a large base to a percentage of customers willing to pay for either performance guarantees or higher service levels (eg professional touchup). There is so much tech out there that a try before you buy (especially if steep learning curve) is the only way to build a large sales funnel. On the other hand, if your 3D scanner is high accuracy then you may want to pitch to industrial users direct and avoid the freemium model (which has limitations). It also depends on the 3D printer workflow (see notes from my 3d-ad brief http://aptn.org.uk/141020%203D%20briefing.php)