[HOT] Suggestions for Helicopter-based Imagery

nicolas chavent nicolas.chavent at gmail.com
Thu Feb 10 09:04:19 GMT 2011


Hi there-

Great to see the development of this thread, just a thought here: it might
be intresting to involve persons from the
OpenAerialMap<http://www.openaerialmap.org/Main_Page>(OAM) project
where those topice have been and are being discussed to
maximise synergies, this also calls for articulating the efforts of both
group when tackling production/processing/use of imagery in crisis responses
when the imagery is not served to osm directly the way yahoo, bing or
spot/unosat did in the past.

Excellent day to all
Nicolas

On Thu, Feb 10, 2011 at 8:00 AM, Milo van der Linden <milo at dogodigi.net>wrote:

> One thing I noticed from Jeffreys pictures of the simple rig is the tape to
> keep the lens in fixed position: there are lenses available with "fixed
> focal length", these would be best to be used for aerial photography! And
> the lenses are only a tiny bit more expensive then regular SLR lenses.
>
> hugin is indeed a good tool for this kind of work, but hugin results depend
> largely on the "known variables", the more known variables you have, the
> better it is.
>
> I was once the secretary of the dutch opengeo stichting (blog.opengeo.nl)
> we had a RC helicopter project running. The fact that the project leader
> failed to publish why aerial photography with rc helicopters was (not)
> possible but simply said: they cannot be used, we will move to building a RC
> plane was amongst one of the reasons for me to quit opengeo.nl
>
> If you take this thing serious and want to set up something general, not
> just for one area; I would gladly introduce you to a couple of contacts of
> mine at ITC Enschede http://www.itc.nl/ a university specialized in
> GeoScience for developing countries.
>
>
> General ideas:
>
> 1. Use a camera with fixed focal length lens (or prime lens)
> 2. Create as much ground control points as possible. Don't forget to take
> height into account.
> 3. Calibrate the camera. Make sure you get the REAL focal length plus all
> other parameters as correct as possible as opposed to what the manufacturer
> gave as focal length
> 4. Try to do as much as possible with hugin, their tool is excelent and
> their community is eager to help out when you can clearly state requirements
> regarding ortho photography
>
> [1] http://en.wikipedia.org/wiki/Prime_lens
> [2] http://www.geo.u-szeged.hu/~joe/fotogrammetria/gcp_specs.htm
> [3] http://hugin.sourceforge.net/tutorials/calibration/en.shtml
> [4] http://hugin.sourceforge.net/
>
>
>
> 2011/2/10 Jeffrey Warren <jeff at unterbahn.com>
>
> What's interesting about that technique is that it uses Hugin to
>> orthorectify imagery but he mentions that he is manually correcting ground
>> control points (GCPs). This almost invalidates the use of hugin, but makes
>> sense since what you really want to do is rectify against a reference map,
>> so that the data doesn't drift.
>>
>> Manual stitching has for the most part proved to be much more accurate,
>> even for large areas, and especially for relatively oblique imagery. (and in
>> fact because in the osm.totor.ph example, he is actually manually moving
>> GCPs, he might be better off using a program which allows a reference layer)
>>
>> Jeff
>>
>>
>> On Thu, Feb 10, 2011 at 12:55 AM, maning sambale <
>> emmanuel.sambale at gmail.com> wrote:
>>
>>> An osmer used this approach in the Philippines:
>>> http://osm.totor.ph/
>>>
>>> On Thu, Feb 10, 2011 at 1:31 PM, george chamales <george at konpagroup.com>
>>> wrote:
>>> > Hello everyone,
>>> > I'm looking for tips / recommendations / suggestions for the ideal way
>>> to
>>> > collect and process photos taken from a helicopter (full-size, not RC)
>>> for
>>> > use in OSM.
>>> > At the very least we'll have a decent point-and-shoot, a gps, and a
>>> > helicopter.  Still waiting to hear what our ceiling is and am trying to
>>> hunt
>>> > down a bubble level.
>>> > Would be great to get some information back soon - there's a
>>> possibility
>>> > that we could be in the air as soon as Friday.
>>> > george
>>> > George Chamales
>>> > Konpa Group
>>> > Mobile: +1 718.288.7718
>>> > Fax:  +1 857.488.4002
>>> > Skype:  notgeorge
>>> > http://konpagroup.com
>>> >
>>> > _______________________________________________
>>> > HOT mailing list
>>> > HOT at openstreetmap.org
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>>> >
>>> >
>>>
>>>
>>>
>>> --
>>> cheers,
>>> maning
>>> ------------------------------------------------------
>>> "Freedom is still the most radical idea of all" -N.Branden
>>> wiki: http://esambale.wikispaces.com/
>>> blog: http://epsg4253.wordpress.com/
>>> ------------------------------------------------------
>>>
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>>
>>
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-- 
Nicolas Chavent
Humanitarian OpenStreetMap Team
http://wiki.openstreetmap.org/wiki/WikiProject_Haiti
Mobile (Haiti): +509 389 583 05
Mobile (France): +33 6 89 45 54 58
Landline (FRA): +33 2 97 26 23 08
Email: nicolas.chavent at gmail.com
Skype: c_nicolas
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