One of the most common questions we receive at Matter & Form are regarding to scan settings; “Which settings should I use?” “Why would I ever use low-density point clouds?” “What does noise reduction do?”
To help, we’ve decided to give some visual examples of how these various settings will impact your scan, as well as describing some uses cases for each of the settings.
There is one key tenet to remember though: ideally, you want to capture your objects with the lowest possible settings that yield optimal results. Each additional tick of the dial creates additional storage and processing demands on your THREE, sometimes exponentially. In rare cases, maxing out all the settings while scanning a complicated object can exhaust system memory and cause your THREE to lose its connection with your computer.
Scan Density
The scan density setting is the most impactful choice you will make when it comes to file size and processing time. The default setting is “Medium”, as we feel this setting has the broadest use case; it will capture most objects quickly, accurately, and efficiently.
However, sometimes you may have outlying cases where the other settings are more appropriate.
Low scan density: There are two main use cases for this setting.
- Simple, smooth objects. If you are scanning an object like a box, where each face is rectangle, there is no benefit to higher scan densities. A low density point cloud will describe this object as accurately as a high density one. This similarly applies to simple curved objects like a mug, vase, ball, etc.
- Scanning larger objects from a distance. Imagine you are scanning a simple, plastic chair, where the priority is accurately capturing the dimensions and general shape. Here, low density scans will be sufficient for this purpose, whereas high density scans will instead reveal things like nicks and surface imperfections in the material.
High scan density: High scan density is best used sparingly, when you need to capture extremely fine details on very small objects; things like the surface of a coin, or the inscription on a ring.
A good rule of thumb is that you will likely want to adjust the scan densities at the extreme ranges of THREE’s working distance. THREE can work capably at a range of 200-800mm; if your object is at 200mm, it may benefit from high scan density, whereas if it’s at 800mm, it will likely not benefit from high (or even medium) scan density.
In this example we have the top of a (fake) skull. This is a relatively smooth, spherical area, and the medium-density scan is more than adequate.
Medium-density scans:
High density scans:
If you look very closely, you can notice some minor increased sharpness in the cracks on top of the skull. However, this minor improvement comes at quite a cost – the high-density project is 1.4GB while the medium density one is only 370 MB, and the processing time is also exponentially longer.
In other circumstances, however, the high-density scan may be crucial to accurately capturing the object. Here is a $1 coin from Canada at low, medium, and high density.
As you can see, with each increase in density, the definition of the text and relief image of Queen Elizabeth II becomes increasingly clear.
Noise Reduction
One of the trade-offs in having a scanner that is capable of capturing incredibly fine details is that it can occasionally misinterpret signal noise for detail, creating surface artifacts that aren’t part of the original object. Here is a comparison Noise Reduction set to 0 and set to 31 for our previous example, the skull.
Noise Reduction = 0
Here the skull has a orange peel quality to it that does not exist on the original object.
Noise Reduction = 31
Here the skull is smooth and the surface details match the original object.
When scanning smooth objects, your scans will benefit from some noise reduction. On objects with fine details and complex textures, you will want the noise reduction setting as low as possible to preserve those.
Pro Tip: Not every scan in a project has to be done at uniform density settings. To save storage space and time, consider scanning the bulk of your object at low or medium density, and then using single shots (non-turntable scans) to capture the areas with fine details.