Common Scan Issues & Resolutions

Understanding the scan process and certain scan results might be tricky at first. In this article, we'll cover the common scan issues and how to resolve them.

Scan Issue: Wobbly Edges / Hole Filling

An important concept to understand with the LF1 scan is "hole-filling." Because the LF1 camera lens and your projector lens can never be in the exact same physical position, there will always be small portions of the scene that can be seen by one lens but not the other. These are referred to as "shadows" or "blindspots."fov_differences.jpg

In the above diagram, the projector is able to see underneath the shelf and plant, but the LF1 can not. This will result in a shadow in the final scan, which is normal.

Automatic Hole-Filling

After a scan is complete, Lightform Creator attempts to fill in these blindspots using a nearest neighbor technique. Essentially, the software samples nearby colors and attempts to fill in the shadows according to nearby values.

However, it is often the case that you will not want hole filling at the maximum setting, because this can cause an effect where your scan has "wobbly edges," making it difficult to create a precise mask.

The solution to wobbly edges is to modify the "Fill" slider after the scan is complete.

Optimal Hole-Filling Technique

In the above video, we demonstrate a technique for getting precise edges in your scan by decreasing the hole filling slider all the way to 0%, then slowly bringing it back up to an amount where your objects are fully filled in, but the shadows are not. In this particular case, around 20%.

hole-fill-100.jpg

Trying to create a precise mask with 100% hole filling, it can sometimes be difficult to determine where the edge of an object is.

hole-fill-19.jpg

With hole-filling set to 19%, we are able to see clearly where the LF1 blindspots are, and therefore create a nice clean mask on the flower.

Scan Issue: Dark & Noisy Scan

projector-color.jpgProjector Scan Result that appears dark and noisy

Problem

When scanning in dark environments, the projector scan result looks dark and noisy.

Solution

Adjust the Brightness slider. After you scan is complete, before you add any surfaces, adjust the "Brightness" slider to blend between the "projector off" and "projector on" scan images.

When the LF1 performs a scan, it produces two final images: one with the projector 100% off, and one with the projector 100% white. In dark environments, the "projector off" image may be under-exposed and appear noisy. You can blend between these images by adjusting the brightness slider. 

ezgif-4-3b1ff07c1213.gif

projector-color1.jpgProjector Scan Result that appears bright and clean

Scan Issue: Movement During Scan

projector-color-1.jpgProjector Scan Result

camera-color.jpgLF1 Camera View

Problem

Sean wanted to show off his cool tropical shirt while we were doing a scan. This caused incorrect graycode correspondences, and affected other regions of the scan. Thanks, Sean. 🙄

Solution

Get Sean outta there! It is important to have no movement in the projection area while performing a scan.

Scan Issue: Reflective Surfaces

projector-color-2.jpgProjector Scan Result

camera-color-1.jpgLF1 Camera View

Problem

Woah, looks like someone was having fun with this one! This scene includes many reflective and transparent materials, which can cause the light of the LF1 graycodes to bounce around and create incorrect correspondences.

Solution 1

Reduce or remove all reflective and transparent surfaces, or rotate them so the light is not being bounced into other areas of the scene.

Solution 2

You can treat reflective surfaces with a temporary dulling spray. This will give them a more matte finish which will scan better.

Here are our recommended dulling sprays:

  1. Krylon Matte Dulling Spray (North America)
    https://www.krylon.com/products/dulling-spray/
  2. K-Line Matt Dulling Spray (Europe)
    https://www.swkenyon.com/matt-dulling-spray.php

Scan Issue: Projector Out of Focus

Capture.pngLive Camera Preview (before scan)

projector-color-3.jpgProjector Scan Result

Problem

The scan result is noisy and has lot of holes. This is because the projector was out of focus, as you can see in theLF1 live camera preview on the top.

Solution 1

When you see the LF1 test pattern before you perform a scan, ensure that the projector is in focus, and you see sharp pixels on the object you are trying to scan.

Scan Issue: Disable Mask

projector-color1-1.jpgProjector Scan Result: "Apply Mask" Enabled

projector-color1-2.jpgProjector Scan Result: "Apply Mask" Disabled

Problem

The top scan has large holes in the corners with long straight edges. This is because the LF1 scan was attempting to automatically mask out areas it thought were too dark or would create bad scan results.

Solution

If you notice large holes with long straight edges, it is typically the case that you need to disable the automatic masking feature. This is accessible before you do a scan in the "Advanced Settings" dropdown. Click the "Apply Mask" button to disable it, then try a new scan.

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Scan Issue: Very Thin Materials

projector-color-4.jpgProjector Scan Result

camera-color-2.jpgLF1 Camera View

Problem

Often times, very thin materials such as string can come out looking wobbly, or not show up at all in a scan.

Solution

If you can see the material in the scan but it looks wobbly, refer to the above solution for "Scan Issue: Wobbly Edges / Hole Filling" If the material is so thin it does not appear at all, then you can try moving the projector closer, or avoid using this material entirely.

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