That' actually above 10 meters according to the manual. But what I was saying is that if there is insufficient light it could cause erratic behavior of the aircraft so flying at dusk into shadows can cause this erratic behavior, according to the manual.
The Vision System cannot work properly over surfaces that do not have clear pattern variations. The
Vision System cannot work properly in any of the following situations. Operate the aircraft cautiously.
a. Flying over monochrome surfaces (e.g., pure black, pure white, pure green).
b. Flying over highly reflective surfaces.
c. Flying over water or transparent surfaces.
d. Flying over moving surfaces or objects.
e. Flying in an area where the lighting changes frequently or drastically.
f. Flying over extremely dark (< 10 lux) or bright (> 40,000 lux) surfaces.
g. Flying over surfaces that strongly reflect or absorb infrared waves (e.g., mirrors).
h. Flying over surfaces without clear patterns or texture.
i. Flying over surfaces with repeating identical patterns or textures (e.g., tiles with the same design).
j. Flying over obstacles with small surface areas (e.g., tree branches).
Keep the sensors clean at all times. DO NOT tamper with the sensors. DO NOT use the aircraft in
environment with dust and humidity. DO NOT obstruct the Infrared Sensing System.
DO NOT fly on days that are rainy, smoggy, or if there is limited visibility.
Flying with no GPS could also cause problems but I have launched with no GPS and I had no problems because the GPS usually engages as soon as the A/C is in the air.
The vision system works between .5m and 30m but what I was saying is that during dusk being low with shadows can affect the vision system because it is too dark. As the aircraft goes higher there is more light available to it, but of course that varies in every location. If you were in the city surrounded by skyscrapers you might not even be able to get high enough to get out of the darkness of the shadows.
I just know, from experience, that if it is too dark the vision system does not work well, or not at all. And if flying over monochrome surfaces (snow) it does not work well.
I was just trying to give cameraz another possibility, I was not saying anyone was right or wrong, and I was not guessing because it did happen to me.