Skywalker Drone Mapping Camera Setup with CHDK

This video covers how I set up my Skywalker FPV plane with a Canon Point and Shoot camera using CHDK scripts triggered by RC transmitter for aerial mapping.

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Comment by c j g on February 19, 2013 at 2:11pm

Thanx for sharing. best .cj

Comment by Phil Walker on June 5, 2013 at 4:38pm

Great video.  I am about to do the same with a Canon SX 230 HS modified for NDVI.  I assume the CHDK would work the same way?  Would you be willing to share your scripts?

Thank you.

Comment by B Duffy on June 6, 2013 at 5:19am
I just modified an sx230 over the weekend and currently testing roscolux #2007 blue filter for generating NDVI from a single camera. It works but needs further investigation to figure out best settings and conditions for image capture. I also have a few other filters on way to test.
Here are some basic NDVI comparisons between an sx230 and an A490, both modified with the Rosco 2007 filter using various image settings on the cameras:

Here's some info on the Rosco material along with aerials from the A490. WB was set to Rosco material for these:

And last but not least, here is the script I use most often. It is very simple and requires a remote trigger controlled by your Tx. You can use an eflight LED light kit soldered to a USB cable to trigger the script. That is what I do.

I'll be posting a video on setting up CHDK to be triggered via Tx as described above but in the meantime if you need any help setting up I'll walk you through the process.
Also, please let me know your NIR plans I want to learn from you too.
Comment by Phil Walker on June 6, 2013 at 7:34pm

Thanks Brenden.  I was at 3D Robotics Berkeley today, and they recommended exactly what you are doing as probably the best way to map for now.  I am going to test my camera over the weekend using a Hex Copter, and on my plane next week when it comes in.  I'll share the pics and details.  Here is the link to where I bought the camera and got it modified

Comment by B Duffy on June 6, 2013 at 7:54pm

Phil, that sounds great!

I have a handful of Canon cameras I'm testing right now and although the Rosco 2007 is generating similar results to the  maxmax Superblue, which I assume is what you purchased, there is still a ton of testing to be done.

I'd love to hear about which camera you are using, how you set your white balance, which image capture settings you use, how you intend to normalize between data sets, correlate NDVI data to ground truth, etc.

I captured some data today using a couple different image capture settings and ran a few NDVI filters on the pics. I'll post the results as soon as I get a chance. I used a Canon SX230 for the flights.

Also, what are you using for post processing?

Ned Horning's Fiji/ImageJ photo monitoring plugin is what I'm currently using. It's free and was made to generate NDVI from individual photos or photo pairs. It's great.

Here is a page I put together to make it easier to grab what you need for the post processing. It really works well and it's a piece of cake to run.

The fellas over at public lab are great to work with! I'm learning a lot.



Comment by B Duffy on June 6, 2013 at 8:06pm

Here is a quick sample... I need to post a bunch of comparison photos with different cameras and camera settings,  and post processing settings as well. Here are some pics from ground test that show different settings with resulting images:

Comment by Phil Walker on June 7, 2013 at 5:36am

I am using a Maxmax modified Canon SX230 HS.  No processing planned as of yet.  I plan to try Microsoft Ice for stitching.  Can you adjust the settings on the Cannon to get this kind of image? 

What I need most immediately is the ability to detect general crop stress.  There are so many universities using the Maxmax setup that I believe there will be a variety of papers detailing how to detect much more in the near future.

Comment by Phil Walker on June 7, 2013 at 9:54am

What do you think of this camera for regular (non IR) mapping photos?  Great price.

Comment by B Duffy on June 7, 2013 at 10:09am
I can't tell by the picture alone what VI they are using but if it is NDVI, which will certainly allow you to quickly identify stressed areas, then it's just a matter of display colors chosen during post processing. With your super blue you will be able to create really nice NDVI outputs and any other VIs that leverage a combination of NIR and either Blue or Green bands. NDVI is usually done with R an NIR but any visible channel works and in this case B is effective.
I will be packaging up an open source NDVI post processing package over the weekend for a client and I'll put a link here. I'll put instructions as well. It's VERY easy.
As for image stitching it's a different story. ICE is sometimes ok, mostly not. I'm still seeking a no cost solution for thi that isn't overly complicated.
Will let you know
Comment by B Duffy on June 7, 2013 at 10:16am
I can't vouch for that camera. I would aim for something with a shutter speed priority mode such as an sx 230 or sx 260. I've had great results with both. I've found that the amount of in focus pictures drops a great deal on many of the lower end point and shoots. Also CHDK can on some cameras allow you to set shutter but I've had very limited results trying this including partial frames. Hope that helps


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