Does anyone know where i can find structured light sources that have the specified characteristics(topic 9 from the document)?
9. Use external projector:
a. While the internal projector is very good, it is really quite low power and is not designed to illuminate very large rooms. It is therefore sometimes beneficial to add one or more additional external projectors. The D4xx camera will benefit from any additional texture projected onto a scene that has no inherent texture, like a flat white wall. Ordinarily, no tuning needs to be done in the D4 VPU when you use any external projectors as long as it is on continuously or flickering at >50KHz, so as not to interfere with the rolling shutter or auto-exposure properties of the sensor.
b. External projectors can be really good in fixed installations where low power consumption is not critical, like a static box measurement device. It is also good for illuminating objects that are far away, by adding illumination nearer to the object.
c. Regarding the specific projection pattern, we recommend somewhere between 5000 and 300,000 semi-random dots. We normally recommend patterns that are scale invariant. This means that if the separation between the projector and the depth sensor changes, then the depth sensor will still see texture across a large range of distances.
d. It is possible to use light in visible or near-infrared (ranging from ~400-1000nm), although we normally recommend 850nm as being a good compromise in being invisible to the human eye while still being visible to the IR sensor with about 15-40% reduction in sensitivity, depending on the sensor used.
e. When using a laser-based projector, it is extremely important to take all means necessary to reduce the laser-speckle or it will adversely affect the depth. Non-coherent light sources will lead to best results in terms of depth noise, but cannot normally generate as high contrast pattern at long range. Even when all speckle reduction methods are employed it is not uncommon to see a passive target or LED projector give >30% better depth than a laser-based projector.
f. Projectors do not need to be co-located with the depth sensor. It is also acceptable to move or shake the projector if desired, but it is not needed.
g. Make sure the projector is eye-safe.
Thank you for any suggestions
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Framos, who are a very reputable supplier of RealSense products, list some structured light projectors.with the 850 nm frequency that the Intel guide recommends and project a pattern that is a cloud of dots.
50% dot density
17% dot density