[OSM-talk] Aerial Photographs (was: People's Map)

[Eric Wolf]

RC airplanes aren't cheaper for two reasons:

1. RC airplanes (and any civilian-operated UAV) has significant flight
restrictions - distance and altitude. Flying at low altitude (under
500 feet MSL), you end up with a higher spatial resolution but you
have to stitch together many more images to cover the same extent as a
single image taken from an aircraft flying at, say, 2000 feet MSL.
Selecting good shots and correcting the imagery for hundreds of images
ends up costing more than the difference in operating an RC plane and
a regular aircraft.

2. RC airplanes crash - often - and they aren't cheap. Sure, regular
airplanes are more expensive but they don't crash as often. A decent
RC rig will set you back $1000+ - not counting the camera.

I used balloons and blimps to do low-altitude aerial photography in my
MS thesis. They are much cheaper than RC planes to operate because
they don't crash (as easily). But you also don't have as much control.
They work really well for taking low-altitude obliques for general
documentation processes. But for creating a basemap of  aerial
imagery, you need to get above the 500 ft MSL barrier put in place by
the FAA. To do this, you have to be in an airplane piloted by a
licensed pilot.

Surprisingly, hiring a light aircraft - like the one used in this
study - is not really all that expensive.

-Eric

-=--=---=----=----=---=--=-=--=---=----=---=--=-=-
Eric B. Wolf                          720-209-6818
USGS Geographer
Center of Excellence in GIScience
PhD Student
CU-Boulder - Geography




On Wed, Apr 15, 2009 at 6:25 PM, Keith Ng <khensthoth at gmail.com> wrote:
> Couldn't the process of obtaining aerial photographs be made much cheaper
> with RC planes? I am not sure if it would work but setting the RC plane on
> auto pilot and attaching a camera with continuous shooting mode might make
> the process simpler.
>
> Also refering to this link, a commentator said:"Just wanted to make it clear
> that we (Pict'Earth) are willing to help anyone from the DIYDrones group to
> get their UAV imagery processed and published in OAM, just let us know. If
> you can fly with a logging GPS and a digicam, our Win32 software will get
> you part of the way and we can help with the rest of the manual bits until
> we get it truly automatic."
>
>
> On Thu, Apr 16, 2009 at 4:06 AM, Blumpsy <blumpsy at yahoo.co.uk> wrote:
>>
>> There is an interesting paper from our dear friends over in Redmond:
>>
>> http://research.microsoft.com/apps/pubs/default.aspx?id=75312
>>
>>  From the article:
>> "Our mission, in contrast, involved an ordinary four seat Cessna
>> ($160/hour rental, including pilot), three feet of PVC pipe, a consumer
>> digital camera ($300), and two people: one pilot and one to operate the
>> camera shutter and change the batteries (Figure 2). In post-processing,
>> we identified 25 ground reference pairs, and used 60 photos to produce a
>> 208 megapixel image at a resolution of 0.15 m/pixel"
>>
>> The camera in Figure 2 looks exactly like the one I have sitting right
>> next to me: a Canon Power Shot A640 with 10MP.
>>
>> I found it rather entertaining to have an operator to press the trigger
>> and swap batteries. For this, there is surely a more elegant solution
>> (PSU and gphoto2)
>>
>> Anyhow, maybe one or the other finds this interesting and inspiring.
>>
>> Cheers
>>
>> Blumpsy
>>
>>
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