Before you start scanning, you'll want to adjust your projector's settings if necessary, set up your physical scene, and select the ideal objects and conditions for the scan.
In this article:
How Lightform Device's Scan Works
Lightform devices use a technique known as visible structured light. This scanning process involves displaying a series of black and white patterns from the projector called graycodes. The Lightform device's camera takes a picture for each unique pattern that is displayed.
These patterns help uniquely identify each one of the projector's pixels. The patterns are displayed for approximately 30 seconds. Once the patterns have finished flashing, the Lightform device will process the images for and assign color values to all projector pixels. The processing phase will take approximately 60 seconds.
This image is the resulting "scan" – essentially a snapshot from the projector's exact point of view.
Additionally, the Lightform device is able to calculate a depth estimate map (a.k.a. disparity), which is the difference between the LF1 camera pixels and projector pixels. While the depth estimate map is not exactly the same thing as true depth, it is still useful in determining distances of objects and enhancing Lightform Creator's effects and selection tools.
Disparity, not depth
Because the Lightform device does not generate metrically accurate depth (distance in standard units, such as meters), it does not create a point cloud, mesh, or other form of 3D model.
There are a few projector settings you may want to change to ensure a proper scan. Settings and menus will vary across different projectors, but the following are generally consistent ones to look out for. If you have the Kit Projector (Epson 1060), we've outlined all our recommended settings here: Recommended Kit Projector Settings.
Ensure horizontal and vertical keystone settings are set to zero. Some projectors have auto-keystone, which should also be disabled.
Disable Auto Keystone
Many projectors have auto-keystone enabled by default, which will adjust the image as you tilt the projector. Look out for that behavior and disable auto-keystone in the menu settings.
Some projectors, including many Epson models, have a physical keystone slider on the top of the lens. This slider can be disabled in the menu settings.
Image Mode, Brightness, and Auto-Iris
Projectors have different image presets usually called "Image Mode" or "Image Preset" that combine settings for brightness, contrast, color balance, tint etc. The Lightform device's camera automatically adjusts its exposure and white balance settings, and should therefore work with most image presets. We recommend picking the image mode that you prefer the final look of.
Brightness & Contrast
In most cases, individual brightness and contrast settings should be left at their default settings. Increasing brightness or contrast too much may result in poor scans.
Auto-Iris & ECO Modes
Many lamp-based projectors have settings designed to extend the life of their halogen bulbs. These settings may be located in the "Image Preset" menu tree, but also in dedicated "Lamp" or "ECO" menus.
We recommend disabling any "Auto-Iris" or "ECO" settings to get the most vibrant projection, but if you wish to extend the life of your projector's bulb (e.g. for permanent installations), you can leave these settings enabled and the Lightform device's scan should still work just fine.
Physical Scene Setup
The following guidelines will help you place your projector relative to your scene, and include general tips on the types of objects and materials that make for great projection surfaces.
When placing your projector relative to your scene, there are a few main concepts to consider.
|Coverage||Is the projector able to cover everything you want to map with the appropriate throw ratio and zoom settings? Use the test card to make sure.|
|Resolution||This is directly related to coverage. Consider that pixels will appear larger and more spread out as you enlarge the projection. You may eventually see individual pixels if viewing from close range.|
|Focus||Is the projector able to focus on all of the objects in your scene? If not, you may need to consider decreasing the overall depth of your scene.|
|Brightness||As your projection image gets larger, you are also reducing the brightness. Insufficient brightness may result in poor scan results. You may get a "not enough correspondences" error if your scene is too dark to scan.|
|Orientation||Is the projector at an extreme angle? This may affect the quality of your content. More on this below.|
Where possible, it is important to avoid extreme or oblique projection angles for three reasons.
- Pixels will become very "stretched" out, making your content look less than optimal. Some projectors with very low depth of field will result in stretched pixels that are out of focus.
- Light may bounce off the oblique surface to other areas of your scene, which can negatively affect the Lightform device's scan. The resulting scan may have holes or incorrect pixel values.
- Brightness falloff may occur, where pixels near the projector are small and very bright, while pixels far away are larger and much dimmer. The Lightform device is able to compensate for uneven scene brightness (HDR) and the difference in pixel size, but if the projector brightness falloff is too extreme, it can confuse the Lightform device's scan.
Avoid extreme projection angles where possible.
An additional consideration is the orientation of the projector's pixel grid relative to your scene. If you tilt your projector, you may start to notice that straight lines have jagged or fuzzy edges. This is because the content is not oriented to the projector's pixels. This effect will be particularly noticeable with small text.
What to Scan
- The Lightform device can scan almost any size scene, from a coffee cup to a building.
- The Lightform device cannot focus on objects closer than 3ft (1m) away.
- If Lightform can see the projected image and the projection is in focus, then it can perform a scan.
- Objects with a dull or matte finish typically scan best.
- You can project on most colored and textured surfaces of any shape.
The following conditions tend to result in a bad scan:
- Glossy, shiny, reflective, or transparent surfaces (e.g., metal, glass, mirrored surfaces)
- Watch out for any nearby surfaces with these properties reflecting light onto your scene. (e.g., sometimes even a shiny table can bounce light. You would want to cover the table with a fabric cloth.)
- Projecting through glass.
- Being too close or far away.
- Surfaces that are too dark or too black (Solution: Bring the surface closer to the projector +Lightform device, try a lighter surface, or try a brighter projector).
- Environment is too bright, too dim, or has too much direct sunlight (Solution: Move to a darker or shaded environment if too bright. Adjust brightness in Scan Properties for dark environments).
- Occlusions: scenes that have many parts that can only be seen by the camera OR the projector, but not both (Solution: These occluded parts of a scene will attempt to be filled in by the hole filling. Try adjusting the "Fill" slider to find the right amount of hole filling).
Some ways to improve a poor scan result:
- Adjust the scan brightness within Lightform Creator after you have taken a scan. Select the Scan Layer in the layers panel on the left and then adjust the Scan Brightness slider on the right as needed.
- Increase the ambient light in the room and take a new scan. We find that it's sometimes better to scan in a brighter room and then turn down the room lights later when you are ready to playback your project.
- Reduce waves/warps by reducing the Scan Property called Fill. This will increase the number of holes but make the scan more accurate.