Photogrammetry with gluonpilot

[blagerst]

Thank you Francisco,
I have now tested programming Survey including trigger command and channel 6 seems to work fine.
However, I will need to rearrange the waypoints to cover my target map.
Looks promising.
/Bo

[Tom]

In the Gluonpilot datalog you can already see the camera trigger. This will be what you need to geotag photos. I am planning to also include it in the telemetry towards the groundstation.

I don't think serial communication with the camera will be possible, unless we use the SPI link, which is also serial. However I do not know of a camera supporting a serial link? For now I just use custom CHDK scripts.

[blagerst]

FLIR-cameras have serial interface and some models with GPS also add location into the images.
/Bo

[kempo]

Hello,

any new updates regarding photogrammetry with gluonpilot ?

Thanks,

Alex

[Tom]

I don' t know about Bo's attempts but photomapping is no problem!

[kempo]

Hi Tom,

It would be possible to add in the Ground Station an option to have the area of the place on which it will be done the survey / photomapping ( to have the value after the polygon fot the survey is build) ?



I have made several trials without any autopilot in very calm weather with a Canon A490 - CHDK , and it seems that 80% of the pictures are blurry.

What camera is used for photomapping by the Gluonpilot Users ?

Thank you,

Alex

[Tom]

Hi Alex,

Thanks for the idea, I'll keep it in mind!

It is important to use a camera that can do shutter priority mode. I put the camera in 1/800th of a second (or whatever gives you good values). The camera itself will adjust the ISO value. This should give you sharper images.

I use a canon ixus 120 with CHDK. The CHDK allows you to use a cheap camera and turn into a more advanced one that can do remote triggering & shutter priority

[fba]

About shutter speed
The basis is that the aircraft movement when the shutter is open must be minus than the pixel size at the scale image sensor.

Example

ground velocity= 20m/s, height =200m, shutter speed = 1/200s, focal length =28mm.

s=vt=20x1/200=0.1m, on the ground

at image scale.

photo escale=focal length/height=0.028/200=1/7142
so movement at camera sensor scale is
s-camera=0.1*(1/7142)=0.000014m=14 microns, so if your camera pixel size is bigger than 14 microns the photos aren´t blurring

Check your: sensor & pixel size, height and average cruised speed to compute the best shutter speed (fixed). Take this suitable configuration: the major time shutter possible, bigger sensor size, the minor ISO speed and high f-number to get the best results.


The extended paper

https://www.asprs.org/wp-content/uploads/pers/2005journal/november/highlight1.pdf
http://www.asprs.org/a/publications/per ... light1.pdf

[Tom]

Thanks for the info. This seems to make sense. But most people have no clue about the image sensor size. Maybe we should include some info for standard cameras such as a canon powershot.

[small_rc]

Maybe there could be a new thread or Forum Subject where people could post their CHDK scripts and details of their cameras.