I see. Thanks for the clarification.<br><br><div class="gmail_quote">On Thu, Apr 16, 2009 at 10:47 AM, Eric Wolf <span dir="ltr"><<a href="mailto:ebwolf@gmail.com">ebwolf@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
RC airplanes aren't cheaper for two reasons:<br>
<br>
1. RC airplanes (and any civilian-operated UAV) has significant flight<br>
restrictions - distance and altitude. Flying at low altitude (under<br>
500 feet MSL), you end up with a higher spatial resolution but you<br>
have to stitch together many more images to cover the same extent as a<br>
single image taken from an aircraft flying at, say, 2000 feet MSL.<br>
Selecting good shots and correcting the imagery for hundreds of images<br>
ends up costing more than the difference in operating an RC plane and<br>
a regular aircraft.<br>
<br>
2. RC airplanes crash - often - and they aren't cheap. Sure, regular<br>
airplanes are more expensive but they don't crash as often. A decent<br>
RC rig will set you back $1000+ - not counting the camera.<br>
<br>
I used balloons and blimps to do low-altitude aerial photography in my<br>
MS thesis. They are much cheaper than RC planes to operate because<br>
they don't crash (as easily). But you also don't have as much control.<br>
They work really well for taking low-altitude obliques for general<br>
documentation processes. But for creating a basemap of aerial<br>
imagery, you need to get above the 500 ft MSL barrier put in place by<br>
the FAA. To do this, you have to be in an airplane piloted by a<br>
licensed pilot.<br>
<br>
Surprisingly, hiring a light aircraft - like the one used in this<br>
study - is not really all that expensive.<br>
<br>
-Eric<br>
<br>
-=--=---=----=----=---=--=-=--=---=----=---=--=-=-<br>
Eric B. Wolf 720-209-6818<br>
USGS Geographer<br>
Center of Excellence in GIScience<br>
PhD Student<br>
CU-Boulder - Geography<br>
<div><div></div><div class="h5"><br>
<br>
<br>
<br>
On Wed, Apr 15, 2009 at 6:25 PM, Keith Ng <<a href="mailto:khensthoth@gmail.com">khensthoth@gmail.com</a>> wrote:<br>
> Couldn't the process of obtaining aerial photographs be made much cheaper<br>
> with RC planes? I am not sure if it would work but setting the RC plane on<br>
> auto pilot and attaching a camera with continuous shooting mode might make<br>
> the process simpler.<br>
><br>
> Also refering to this link, a commentator said:"Just wanted to make it clear<br>
> that we (Pict'Earth) are willing to help anyone from the DIYDrones group to<br>
> get their UAV imagery processed and published in OAM, just let us know. If<br>
> you can fly with a logging GPS and a digicam, our Win32 software will get<br>
> you part of the way and we can help with the rest of the manual bits until<br>
> we get it truly automatic."<br>
><br>
><br>
> On Thu, Apr 16, 2009 at 4:06 AM, Blumpsy <<a href="mailto:blumpsy@yahoo.co.uk">blumpsy@yahoo.co.uk</a>> wrote:<br>
>><br>
>> There is an interesting paper from our dear friends over in Redmond:<br>
>><br>
>> <a href="http://research.microsoft.com/apps/pubs/default.aspx?id=75312" target="_blank">http://research.microsoft.com/apps/pubs/default.aspx?id=75312</a><br>
>><br>
>> From the article:<br>
>> "Our mission, in contrast, involved an ordinary four seat Cessna<br>
>> ($160/hour rental, including pilot), three feet of PVC pipe, a consumer<br>
>> digital camera ($300), and two people: one pilot and one to operate the<br>
>> camera shutter and change the batteries (Figure 2). In post-processing,<br>
>> we identified 25 ground reference pairs, and used 60 photos to produce a<br>
>> 208 megapixel image at a resolution of 0.15 m/pixel"<br>
>><br>
>> The camera in Figure 2 looks exactly like the one I have sitting right<br>
>> next to me: a Canon Power Shot A640 with 10MP.<br>
>><br>
>> I found it rather entertaining to have an operator to press the trigger<br>
>> and swap batteries. For this, there is surely a more elegant solution<br>
>> (PSU and gphoto2)<br>
>><br>
>> Anyhow, maybe one or the other finds this interesting and inspiring.<br>
>><br>
>> Cheers<br>
>><br>
>> Blumpsy<br>
>><br>
>><br>
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