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Author Topic: Forest and Water Area  (Read 3704 times)

Reno2015

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Forest and Water Area
« on: December 18, 2015, 09:31:05 AM »
hello friends,

i have project in borneo island of Indonesia country
this project area consist most of water and forest area
i flew with skywalker and cannon s100 camera and 150-200 meters AGL
i took images every 4 seconds
i have reject every oblique and blur images
when i processed with AGI ver 1.2 at high align parameter, it was not constructed, like no pattern
so no better result for this
second try, at highest align parameter and 200000 key point limit and 20000 tie point
and the result was still the same
the results were not so satisfactory, no pattern, and not in accordance with the original situation in the field and sometimes the results were not connected
any idea what should i do to complete the process?
need help,

Thanks in Advance,

Wishgranter

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Re: Forest and Water Area
« Reply #1 on: December 18, 2015, 02:02:56 PM »
set 200k in detection and use just 20k tie point limits = you set to detect lot of features but use just 10 % try set tie point to higher number 50-100k and report back
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Reno2015

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Re: Forest and Water Area
« Reply #2 on: December 19, 2015, 04:44:22 PM »
set 200k in detection and use just 20k tie point limits = you set to detect lot of features but use just 10 % try set tie point to higher number 50-100k and report back

still got same result, the difference result was on number of camera aligned,
on previous try is just 64 photo aligned
and at your advice align parameter 111,

thanks sir for give me some advice, :)

but maybe the solution is re-fly and take mission again at higher altitude
i'll change at 300-450 meters AGL, that means the photo has wider coverage

Packy_GIS

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Re: Forest and Water Area
« Reply #3 on: December 19, 2015, 11:31:11 PM »
If there is a lot of water in the area, make sure that on each picture there is visible a bit of land/trees so the images can be aligned. You will never align moving water. The higher altitude is a good plan. What you should do before you start your mission is - based on the lens you are using and the flight altitude compute the area that will be visible on the picture. Draw in GIS lines (of flight) and make sure, that the images in the neigboring lines do overlap. I that upload the GIS data into my GPS and I fly along the lines - this makes sure that there is sufficient side-overlap. I don't know how fast you fly - maybe you should take picture faster then every 4s.
It is always better to processes properly obtaine data.
Packy

radioactivepanda

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Re: Forest and Water Area
« Reply #4 on: December 19, 2015, 11:54:22 PM »
Hi Reno,

I know it may sound a bit counter productive, however I had similar situation: coverage of 1sqKm of archaeological site area, with olympus e-pl5 camera. Flight overlap (which is always a thing to consider) was 80% forward, 60% sideways, forested area (no running water though).

I would have preferred more side overlap, however I was just hiring a crew and I presumed that they knew well enough. Photos were always in nadir, and all bad ones have been eliminated.

On multiple occasions I failed generating aligned data with high parameter, with more settings used than i care to remember. What was successful was, setting alignment on medium, with some standard keypont/tiepoint relation. Now> I am still in procedure of establishing if this produced good quality, or good enough quality dataset. Perhaps you would like to try it out. So far, I saw no reason to be dissatisfied - i believe that using GCP and bundle adjustment after the alignment operation, corrects any erroneous reconstruction.

And it also, by the looks of screenshot, you might have issues with overlap of the photos. More dense camera network should solve the things.

In any case, test some options, im sure there will be a simple solution.

best regards