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Author Topic: infite orthophoto  (Read 11996 times)

kiteman

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infite orthophoto
« on: August 01, 2012, 05:44:36 PM »
from a Merged chunk of an area 500 meters x 650 meters ( 457 photos taken with sony nex 5n,  ) I try to obtain a orthophoto, but after a night of work,  the process only at 2 % and less 438 hours!

My pc have 12 GB of ram and 64 bit W7

I tried to cut, the point clouds, in five small box but the process is very slow, too.

Do you have some ideas? For a more quick orthophoto?
Many thanks
Stefano


Wishgranter

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Re: infite orthophoto
« Reply #1 on: August 01, 2012, 06:13:56 PM »
what resolution have the photos and what setting are you used on reconstruction ? HIGH, ULTRA ??

what reconstruction method is used ? Height field or arbitrary ?
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Alexey Pasumansky

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Re: infite orthophoto
« Reply #2 on: August 01, 2012, 06:21:32 PM »
Hello Stefano,

What is the target orthophoto resolution? And maybe you can see the grid size in Console pane?
Best regards,
Alexey Pasumansky,
Agisoft LLC

kiteman

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Re: infite orthophoto
« Reply #3 on: August 02, 2012, 08:51:45 AM »
resolution the photos is     4912 x 3264
reconstruction low
Arbitrary
0

Alexey Pasumansky

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Re: infite orthophoto
« Reply #4 on: August 02, 2012, 11:23:11 AM »
Hello Stefano,

So yo have got problems at Build geometry stage and not during export orthophoto?

Then you should better use Height Field reconstruction method since it has optimizations for aerial photo processing.
And you can also try version 0.9.0, but please note that zero value in Face count field for Height field methods have not different meaning and for maximal faces in the target model  intentionally higher values should be used (100M for example).
Best regards,
Alexey Pasumansky,
Agisoft LLC

kiteman

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Re: infite orthophoto
« Reply #5 on: August 02, 2012, 04:21:06 PM »
"Hello Stefano,

What is the target orthophoto resolution? And maybe you can see the grid size in Console pane?"

The target orthophoto resolution is about 3 cm.

grid size? now I search..

kiteman

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Re: infite orthophoto
« Reply #6 on: August 02, 2012, 04:23:30 PM »
"So yo have got problems at Build geometry stage and not during export orthophoto?"

I have problem only during export photo.

The new version 0.9.0, is more fast to export ortho? Now I try, many thanks for info

Alexey Pasumansky

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Re: infite orthophoto
« Reply #7 on: August 02, 2012, 04:29:17 PM »
Hello Stefano,

Quote
The target orthophoto resolution is about 3 cm.
Then maybe your system doesn't have enough memory for processing orthophoto in single file. Maybe you'd better use "Split in blocks" feature in the Export Orthophoto dialog.
Best regards,
Alexey Pasumansky,
Agisoft LLC

kiteman

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Re: infite orthophoto
« Reply #8 on: August 02, 2012, 04:36:52 PM »
Itry to split, but it's the same.

now i try heigh field with version 0.9.0

Alexey Pankov

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Re: infite orthophoto
« Reply #9 on: August 02, 2012, 06:01:43 PM »
Normally such an ultra slow processing takes place when there is not enough RAM. System starts to use scracth file and it makes processing thousands times slower. So first I would suggest you to watch RAM consumption when you working on this project.

But I'm still wondering why it happened in your project.
500 x 600 meters at 3 cm per pixel is just about 300MPx image. 12 Gb RAM should be enough to process it even in single block.
Low quality model also shouldn't consume much memory. But wait a moment...
457 photos in Arbitraty mode even at low quality may produce quite large model, that consists of dozens of millions of polygons. How many polygons are in your model?

If there are too many (when just the visualization of the model consumes more than half of RAM), then you should go for a smaller model (in number of polygons). There are number of options for it:
 - height field mode (normally it produces lower polygons model, than arbitrary mode);
 - lower quality of reconstruction;
 - splitting model in separate chunks, setting smaller processing boxes in each of them, then building individual smaller size models and exporting separate orthophoto blocks from these individual models (if all the models come from the same point cloud then orthophotos should match well).

Btw, how did you come to the merged chunk - have you built the models in separate chunk and then merged the models or you built the model after merging chunks?

kiteman

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Re: infite orthophoto
« Reply #10 on: August 03, 2012, 09:43:47 AM »
Hi Alexey,


In the model there are 132 millions  of polygons.

Now in heigt field, with version 0.9.0 I put 60 millions .

I built the model in separate chunk, I georeferencing the singolar chunk, I merged the chunck and after I buit the model

Wishgranter

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Re: infite orthophoto
« Reply #11 on: August 03, 2012, 11:28:39 AM »
what is effective overlap of the images ? see INFO under the CHUNK.....
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Alexey Pankov

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Re: infite orthophoto
« Reply #12 on: August 03, 2012, 01:15:54 PM »
Now in heigt field, with version 0.9.0 I put 60 millions .
Well, accordig to Memory Requirements there is a good chance that 12 Gb RAM will be enough to decimate 60M mesh. Try to decimate it to few millions and then export orthophoto.
If you succeed with decimation there should be no problems with export.

kiteman

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Re: infite orthophoto
« Reply #13 on: August 03, 2012, 01:46:47 PM »
Effective overlap : 3. 03

OK.. I will try to decimate to 10 millions, and then export. Many thanks at all

Wishgranter

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Re: infite orthophoto
« Reply #14 on: August 05, 2012, 09:10:29 PM »
Overlap is 3.0 that mean you have a too much images, you can try to work with lower amount of photos - so you get a lower polycount
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