Hi, very late to this thread and Nicholas may have already flown this last Friday, but I have a few thoughts. The suggestions already given by others look great.<div>Miko is correct about a prime lens/fixed focal length being most optimal. The Canon point and shoot cameras that you do mention will work OK if that is all you have access too. </div>
<div>I could help you do the full calculation for those two Canons, but as a point of reference here is a typical Swath calculation from a Cannon G10</div><p style="margin: 0.0px 0.0px 0.0px 0.0px; font: 12.0px Helvetica; min-height: 14.0px">
<br></p>
<table cellspacing="0" cellpadding="0" style="background-color: #ffffff; border-collapse: collapse">
<tbody>
<tr>
<td valign="bottom" style="width: 140.0px; height: 14.0px; background-color: #aca9fd; border-style: solid; border-width: 1.0px 1.0px 1.0px 1.0px; border-color: #000000 #000000 #000000 #000000; padding: 0.0px 2.0px 0.0px 2.0px">
<p style="margin: 0.0px 0.0px 0.0px 0.0px; text-align: center; font: 9.0px Arial"><span style="letter-spacing: 0.0px"><b>MODEL</b></span></p>
</td>
<td valign="bottom" style="width: 155.0px; height: 14.0px; background-color: #aca9fd; border-style: solid; border-width: 1.0px 1.0px 1.0px 1.0px; border-color: #000000 #000000 #000000 #000000; padding: 0.0px 2.0px 0.0px 2.0px">
<p style="margin: 0.0px 0.0px 0.0px 0.0px; text-align: center; font: 9.0px Arial"><span style="letter-spacing: 0.0px"><b>ELEVATION in M</b></span></p>
</td>
<td valign="bottom" style="width: 152.0px; height: 14.0px; background-color: #aca9fd; border-style: solid; border-width: 1.0px 1.0px 1.0px 1.0px; border-color: #000000 #000000 #000000 #000000; padding: 0.0px 2.0px 0.0px 2.0px">
<p style="margin: 0.0px 0.0px 0.0px 0.0px; text-align: center; font: 9.0px Arial"><span style="letter-spacing: 0.0px"><b>SWATH in M</b></span></p>
</td>
<td valign="bottom" style="width: 128.0px; height: 14.0px; background-color: #aca9fd; border-style: solid; border-width: 1.0px 1.0px 1.0px 1.0px; border-color: #000000 #000000 #000000 #000000; padding: 0.0px 2.0px 0.0px 2.0px">
<p style="margin: 0.0px 0.0px 0.0px 0.0px; text-align: center; font: 9.0px Arial"><span style="letter-spacing: 0.0px"><b>SURFACE Ha</b></span></p>
</td>
<td valign="bottom" style="width: 124.0px; height: 14.0px; background-color: #aca9fd; border-style: solid; border-width: 1.0px 1.0px 1.0px 1.0px; border-color: #000000 #000000 #000000 #000000; padding: 0.0px 2.0px 0.0px 2.0px">
<p style="margin: 0.0px 0.0px 0.0px 0.0px; text-align: center; font: 9.0px Arial"><span style="letter-spacing: 0.0px"><b>RESOLUTION CM</b></span></p>
</td>
</tr>
<tr>
<td rowspan="6" valign="middle" style="width: 140.0px; height: 71.0px; border-style: solid; border-width: 1.0px 1.0px 1.0px 1.0px; border-color: #000000 #000000 #000000 #000000; padding: 0.0px 2.0px 0.0px 2.0px">
<p style="margin: 0.0px 0.0px 0.0px 0.0px; text-align: center; font: 10.0px Arial"><span style="letter-spacing: 0.0px"><b>CANON G10</b></span></p>
</td>
<td valign="bottom" style="width: 155.5px; height: 12.2px; background-color: #feffd7; border-style: solid; border-width: 1.0px 0.0px 0.0px 1.0px; border-color: #000000 transparent transparent #000000; padding: 0.0px 2.0px 0.0px 2.0px">
<p style="margin: 0.0px 0.0px 0.0px 0.0px; text-align: right; font: 10.0px Arial"><span style="letter-spacing: 0.0px">100</span></p>
</td>
<td valign="bottom" style="width: 153.0px; height: 12.2px; background-color: #feffd7; border-style: solid; border-width: 1.0px 0.0px 0.0px 0.0px; border-color: #000000 transparent transparent transparent; padding: 0.0px 2.0px 0.0px 2.0px">
<p style="margin: 0.0px 0.0px 0.0px 0.0px; text-align: right; font: 10.0px Arial"><span style="letter-spacing: 0.0px">124.590163934426</span></p>
</td>
<td valign="bottom" style="width: 129.0px; height: 12.2px; background-color: #feffd7; border-style: solid; border-width: 1.0px 0.0px 0.0px 0.0px; border-color: #000000 transparent transparent transparent; padding: 0.0px 2.0px 0.0px 2.0px">
<p style="margin: 0.0px 0.0px 0.0px 0.0px; text-align: right; font: 10.0px Arial"><span style="letter-spacing: 0.0px">1.16420317119054</span></p>
</td>
<td valign="bottom" style="width: 124.5px; height: 12.2px; background-color: #feffd7; border-style: solid; border-width: 1.0px 1.0px 0.0px 0.0px; border-color: #000000 #000000 transparent transparent; padding: 0.0px 2.0px 0.0px 2.0px">
<p style="margin: 0.0px 0.0px 0.0px 0.0px; text-align: right; font: 10.0px Arial"><span style="letter-spacing: 0.0px">2.8</span></p>
</td>
</tr>
<tr>
<td valign="bottom" style="width: 155.5px; height: 8.2px; background-color: #feffd7; border-style: solid; border-width: 0.0px 0.0px 0.0px 1.0px; border-color: transparent transparent transparent #000000; padding: 0.0px 2.0px 0.0px 2.0px">
<p style="margin: 0.0px 0.0px 0.0px 0.0px; text-align: right; font: 10.0px Arial"><span style="letter-spacing: 0.0px">200</span></p>
</td>
<td valign="bottom" style="width: 153.0px; height: 8.2px; background-color: #feffd7; padding: 0.0px 2.0px 0.0px 2.0px">
<p style="margin: 0.0px 0.0px 0.0px 0.0px; text-align: right; font: 10.0px Arial"><span style="letter-spacing: 0.0px">249.180327868853</span></p>
</td>
<td valign="bottom" style="width: 129.0px; height: 8.2px; background-color: #feffd7; padding: 0.0px 2.0px 0.0px 2.0px">
<p style="margin: 0.0px 0.0px 0.0px 0.0px; text-align: right; font: 10.0px Arial"><span style="letter-spacing: 0.0px">4.65681268476216</span></p>
</td>
<td valign="bottom" style="width: 124.5px; height: 8.2px; background-color: #feffd7; border-style: solid; border-width: 0.0px 1.0px 0.0px 0.0px; border-color: transparent #000000 transparent transparent; padding: 0.0px 2.0px 0.0px 2.0px">
<p style="margin: 0.0px 0.0px 0.0px 0.0px; text-align: right; font: 10.0px Arial"><span style="letter-spacing: 0.0px">5.6</span></p>
</td>
</tr>
<tr>
<td valign="bottom" style="width: 155.5px; height: 12.8px; background-color: #feffd7; border-style: solid; border-width: 0.0px 0.0px 0.0px 1.0px; border-color: transparent transparent transparent #000000; padding: 0.0px 2.0px 0.0px 2.0px">
<p style="margin: 0.0px 0.0px 0.0px 0.0px; text-align: right; font: 10.0px Arial"><span style="letter-spacing: 0.0px">300</span></p>
</td>
<td valign="bottom" style="width: 153.0px; height: 12.8px; background-color: #feffd7; padding: 0.0px 2.0px 0.0px 2.0px">
<p style="margin: 0.0px 0.0px 0.0px 0.0px; text-align: right; font: 10.0px Arial"><span style="letter-spacing: 0.0px">373.770491803279</span></p>
</td>
<td valign="bottom" style="width: 129.0px; height: 12.8px; background-color: #feffd7; padding: 0.0px 2.0px 0.0px 2.0px">
<p style="margin: 0.0px 0.0px 0.0px 0.0px; text-align: right; font: 10.0px Arial"><span style="letter-spacing: 0.0px">10.4778285407149</span></p>
</td>
<td valign="bottom" style="width: 124.5px; height: 12.8px; background-color: #feffd7; border-style: solid; border-width: 0.0px 1.0px 0.0px 0.0px; border-color: transparent #000000 transparent transparent; padding: 0.0px 2.0px 0.0px 2.0px">
<p style="margin: 0.0px 0.0px 0.0px 0.0px; text-align: right; font: 10.0px Arial"><span style="letter-spacing: 0.0px">8.5</span></p>
</td>
</tr>
<tr>
<td valign="bottom" style="width: 155.5px; height: 12.8px; background-color: #feffd7; border-style: solid; border-width: 0.0px 0.0px 0.0px 1.0px; border-color: transparent transparent transparent #000000; padding: 0.0px 2.0px 0.0px 2.0px">
<p style="margin: 0.0px 0.0px 0.0px 0.0px; text-align: right; font: 10.0px Arial"><span style="letter-spacing: 0.0px">500</span></p>
</td>
<td valign="bottom" style="width: 153.0px; height: 12.8px; background-color: #feffd7; padding: 0.0px 2.0px 0.0px 2.0px">
<p style="margin: 0.0px 0.0px 0.0px 0.0px; text-align: right; font: 10.0px Arial"><span style="letter-spacing: 0.0px">622.950819672131</span></p>
</td>
<td valign="bottom" style="width: 129.0px; height: 12.8px; background-color: #feffd7; padding: 0.0px 2.0px 0.0px 2.0px">
<p style="margin: 0.0px 0.0px 0.0px 0.0px; text-align: right; font: 10.0px Arial"><span style="letter-spacing: 0.0px">29.1050792797635</span></p>
</td>
<td valign="bottom" style="width: 124.5px; height: 12.8px; background-color: #feffd7; border-style: solid; border-width: 0.0px 1.0px 0.0px 0.0px; border-color: transparent #000000 transparent transparent; padding: 0.0px 2.0px 0.0px 2.0px">
<p style="margin: 0.0px 0.0px 0.0px 0.0px; text-align: right; font: 10.0px Arial"><span style="letter-spacing: 0.0px">14.1</span></p>
</td>
</tr>
<tr>
<td valign="bottom" style="width: 155.5px; height: 12.2px; background-color: #feffd7; border-style: solid; border-width: 0.0px 0.0px 1.0px 1.0px; border-color: transparent transparent #000000 #000000; padding: 0.0px 2.0px 0.0px 2.0px">
<p style="margin: 0.0px 0.0px 0.0px 0.0px; text-align: right; font: 10.0px Arial"><span style="letter-spacing: 0.0px">1000</span></p>
</td>
<td valign="bottom" style="width: 153.0px; height: 12.2px; background-color: #feffd7; border-style: solid; border-width: 0.0px 0.0px 1.0px 0.0px; border-color: transparent transparent #000000 transparent; padding: 0.0px 2.0px 0.0px 2.0px">
<p style="margin: 0.0px 0.0px 0.0px 0.0px; text-align: right; font: 10.0px Arial"><span style="letter-spacing: 0.0px">1245.90163934426</span></p>
</td>
<td valign="bottom" style="width: 129.0px; height: 12.2px; background-color: #feffd7; border-style: solid; border-width: 0.0px 0.0px 1.0px 0.0px; border-color: transparent transparent #000000 transparent; padding: 0.0px 2.0px 0.0px 2.0px">
<p style="margin: 0.0px 0.0px 0.0px 0.0px; text-align: right; font: 10.0px Arial"><span style="letter-spacing: 0.0px">116.420317119054</span></p>
</td>
<td valign="bottom" style="width: 124.5px; height: 12.2px; background-color: #feffd7; border-style: solid; border-width: 0.0px 1.0px 1.0px 0.0px; border-color: transparent #000000 #000000 transparent; padding: 0.0px 2.0px 0.0px 2.0px">
<p style="margin: 0.0px 0.0px 0.0px 0.0px; text-align: right; font: 10.0px Arial"><span style="letter-spacing: 0.0px">28.2</span></p>
</td>
</tr>
<tr>
<td valign="bottom" style="width: 155.5px; height: 11.8px; background-color: #e99894; border-style: solid; border-width: 1.0px 0.0px 1.0px 1.0px; border-color: #000000 transparent #000000 #000000; padding: 0.0px 2.0px 0.0px 2.0px">
<p style="margin: 0.0px 0.0px 0.0px 0.0px; text-align: right; font: 10.0px Arial"><span style="letter-spacing: 0.0px">1500</span></p>
</td>
<td valign="bottom" style="width: 153.0px; height: 11.8px; background-color: #e99894; border-style: solid; border-width: 1.0px 0.0px 1.0px 0.0px; border-color: #000000 transparent #000000 transparent; padding: 0.0px 2.0px 0.0px 2.0px">
<p style="margin: 0.0px 0.0px 0.0px 0.0px; text-align: right; font: 10.0px Arial"><span style="letter-spacing: 0.0px">1868.85245901639</span></p>
</td>
<td valign="bottom" style="width: 129.0px; height: 11.8px; background-color: #e99894; border-style: solid; border-width: 1.0px 0.0px 1.0px 0.0px; border-color: #000000 transparent #000000 transparent; padding: 0.0px 2.0px 0.0px 2.0px">
<p style="margin: 0.0px 0.0px 0.0px 0.0px; text-align: right; font: 10.0px Arial"><span style="letter-spacing: 0.0px">261.945713517872</span></p>
</td>
<td valign="bottom" style="width: 124.5px; height: 11.8px; background-color: #e99894; border-style: solid; border-width: 1.0px 1.0px 1.0px 0.0px; border-color: #000000 #000000 #000000 transparent; padding: 0.0px 2.0px 0.0px 2.0px">
<p style="margin: 0.0px 0.0px 0.0px 0.0px; text-align: right; font: 10.0px Arial"><span style="letter-spacing: 0.0px">42.3</span></p>
</td>
</tr>
</tbody>
</table>
<p style="margin: 0.0px 0.0px 0.0px 0.0px; font: 12.0px Helvetica; min-height: 14.0px"><br></p><div> I am not sure what you spatial resolution requirements are, but the higher you fly, the easier it will be to process the imagery. Holding the camera in a consistent geodata position is critical. The bubble level should help dampen vibrations. I simple hold onto the rubber clamp to reduce the vibrations. Depending on the type of heli, it may be possible to use the same simple rubber clamp configuration. This clamp is easy to set up, but it really depends on the type of aircraft and coordination with the pilot.</div>
<div><br></div><div>Sufficient overlap amongst the images makes for a better map, but if you are georeferencing and rectifying the images while focusing on the ground of the scene, it is OK to include oblique perspectives on 3d objects like buildings and trees. You just need to make sure that the actual ground is positioned correctly. In an optimal situation there is >80% overlap, and a subset of each image is made to crop out area that are off the vertical axis. If there is less data, or you would like to include more information with the oblique stuff on the periphery of the imagery that is fine too, keeping in mind that you are correcting for the ground and not vertical objects.</div>
<div><br></div><div>Good Luck!</div><div>Stewart</div><div>-let me know if you have more questions, or if you want me to take a look at the raw data for processing...</div><div><br></div><div><br></div><div><br><div class="gmail_quote">
On Thu, Feb 10, 2011 at 1:04 AM, nicolas chavent <span dir="ltr"><<a href="mailto:nicolas.chavent@gmail.com">nicolas.chavent@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
Hi there-<br><br>Great to see the development of this thread, just a thought here: it might be intresting to involve persons from the <a href="http://www.openaerialmap.org/Main_Page" target="_blank">OpenAerialMap</a> (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. <br>
<br>Excellent day to all<br>Nicolas<div><div></div><div class="h5"><br><br><div class="gmail_quote">On Thu, Feb 10, 2011 at 8:00 AM, Milo van der Linden <span dir="ltr"><<a href="mailto:milo@dogodigi.net" target="_blank">milo@dogodigi.net</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0pt 0pt 0pt 0.8ex;border-left:1px solid rgb(204, 204, 204);padding-left:1ex">
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.<br>
<br>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.<br><br>I was once the secretary of the dutch opengeo stichting (<a href="http://blog.opengeo.nl" target="_blank">blog.opengeo.nl</a>) 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 <a href="http://opengeo.nl" target="_blank">opengeo.nl</a><br>
<br>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 <a href="http://www.itc.nl/" target="_blank">http://www.itc.nl/</a> a university specialized in GeoScience for developing countries.<br>
<br><br>General ideas:<br><br>1. Use a camera with fixed focal length lens (or prime lens)<br>2. Create as much ground control points as possible. Don't forget to take height into account.<br>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<br>
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<br><br>[1] <a href="http://en.wikipedia.org/wiki/Prime_lens" target="_blank">http://en.wikipedia.org/wiki/Prime_lens</a><br>
[2] <a href="http://www.geo.u-szeged.hu/%7Ejoe/fotogrammetria/gcp_specs.htm" target="_blank">http://www.geo.u-szeged.hu/~joe/fotogrammetria/gcp_specs.htm</a> <br>[3] <a href="http://hugin.sourceforge.net/tutorials/calibration/en.shtml" target="_blank">http://hugin.sourceforge.net/tutorials/calibration/en.shtml</a><br>
[4] <a href="http://hugin.sourceforge.net/" target="_blank">http://hugin.sourceforge.net/</a><br><br><br><br><div class="gmail_quote">2011/2/10 Jeffrey Warren <span dir="ltr"><<a href="mailto:jeff@unterbahn.com" target="_blank">jeff@unterbahn.com</a>></span><div>
<div></div><div><br>
<blockquote class="gmail_quote" style="margin:0pt 0pt 0pt 0.8ex;border-left:1px solid rgb(204, 204, 204);padding-left:1ex">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. <div>
<br></div><div>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 <a href="http://osm.totor.ph" target="_blank">osm.totor.ph</a> example, he is actually manually moving GCPs, he might be better off using a program which allows a reference layer)</div>
<div><br></div><div>Jeff<div><div></div><div><br><br><div class="gmail_quote">On Thu, Feb 10, 2011 at 12:55 AM, maning sambale <span dir="ltr"><<a href="mailto:emmanuel.sambale@gmail.com" target="_blank">emmanuel.sambale@gmail.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0pt 0pt 0pt 0.8ex;border-left:1px solid rgb(204, 204, 204);padding-left:1ex">An osmer used this approach in the Philippines:<br>
<a href="http://osm.totor.ph/" target="_blank">http://osm.totor.ph/</a><br>
<div><div></div><div><br>
On Thu, Feb 10, 2011 at 1:31 PM, george chamales <<a href="mailto:george@konpagroup.com" target="_blank">george@konpagroup.com</a>> wrote:<br>
> Hello everyone,<br>
> I'm looking for tips / recommendations / suggestions for the ideal way to<br>
> collect and process photos taken from a helicopter (full-size, not RC) for<br>
> use in OSM.<br>
> At the very least we'll have a decent point-and-shoot, a gps, and a<br>
> helicopter. Still waiting to hear what our ceiling is and am trying to hunt<br>
> down a bubble level.<br>
> Would be great to get some information back soon - there's a possibility<br>
> that we could be in the air as soon as Friday.<br>
> george<br>
> George Chamales<br>
> Konpa Group<br>
> Mobile: +1 718.288.7718<br>
> Fax: +1 857.488.4002<br>
> Skype: notgeorge<br>
> <a href="http://konpagroup.com" target="_blank">http://konpagroup.com</a><br>
><br>
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<br></blockquote></div><br><br clear="all"><br>-- <br></div></div>Nicolas Chavent<br>Humanitarian OpenStreetMap Team<br><a href="http://wiki.openstreetmap.org/wiki/WikiProject_Haiti" target="_blank">http://wiki.openstreetmap.org/wiki/WikiProject_Haiti</a><br>
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