Messages

31

General / Re: Fixing that area where the point cloud is poor

« on: July 10, 2015, 07:17:39 PM »

Currently learning the whole Chunk method and finding YouTube videos to see if this is what I needed.  Out of Memory happened at all my Mesh stages, so this Chunking is probably what I need to do here.

32

General / Fixing that area where the point cloud is poor

« on: July 09, 2015, 12:50:48 AM »

(Cameras are 9MP Lumeneras, flown at 450m AGL)

The ultra high point cloud looks great for most of my mosaic (used high quality alignment), but certain areas need some help.  (PS this same field was flown last year with Canon S-95 cameras and my ultra high point cloud was very good with one run, none of this noisy stuff or cliff dropping...)

 
I was sent these instructions from Agisoft:

As a workaround we can suggest the following procedure, though it seems quite complicated:
1 duplicate the chunk after building the dense cloud in original one,
2 make new chunk active,
3 shrink the bounding box to the problematic area,
4 rebuild dense cloud with new settings, providing that it is possible,
5 disable or remove all cameras from this chunk,
6 cut corresponding points of the dense cloud in the original chunk,
7 merge chunks (with merge dense clouds option on).


Summarized by someone else:

You can duplicate the chunk, shrink the bounding box, build mesh, remove dense cloud (in the duplicated chunk), repeat the operation with the different bounding box sizes. Merge duplicated chunks.

I'm at step 4 (after making a smaller bounding box area) and not sure why use NEW settings as I want ultra high and mild.  Everything still looks poor no matter which settings I choose.

What to do here?  Is this where it's supposed to look better?

Haven't even arrived at the merge chunks yet...

33

General / Re: Point cloud density over trees

« on: May 21, 2015, 08:11:51 PM »

I get the same results Rob - Lowest actually populates the trees but sparsely.  Posting to follow along for more info!

When I make orthophotos, I actually classify all the ground points and make my mosaic on that so not including the trees is OK for those types of orthophotos (which will eliminated the wavy or drop off appearances with tress/buildings).

34

General / Re: Digitisation workflow for historical aerial photographs...

« on: May 20, 2015, 10:54:44 PM »

This summer I will embark on a very similar project with a LOT of photos. haven't figured out my plan of action yet.

I did get some scanner recommendations from the USDA-FSA-Aerial Photography Field Office as far as using a large format reflective scanner, from his email:

Hard copy photos will need a reflective scanner.  Most flatbed scanners are about 8.5” x 12”.  Since your aerial photos are approximately 9.5” x 9.5” you will need to determine if a standard scanner would cut off too much of the photo or if you could consider a scanner designed for larger documents.  These are often 11” x 17” or larger.  Like traditional scanners the price can vary drastically.  Flatbed scanner designed for larger documents.  Some examples can be seen at:
http://www.amazon.com/s?ie=UTF8&page=1&rh=i%3Aaps%2Ck%3Alarge%20document%20scanner
 
My recommendation would be that you investigate:

++ Traditional 8.5 x 11 scanners (may not get the edges but aerial photography usually has 30 – 70% overlap)
++ Large document scanner 
++ Take photographs of the photos with a DSLR camera and use these as your scanned image.  This could work well, especially if you build a frame to keep the angle and distance consistent.[/li][/list]

 
Remember that paper photos may or may not have the PPI (points per inch) that would enable a 15 micron (1693 dpi) scan.  Film will almost always have a much higher level of resolving capability than a paper photograph.
 
 
 

35

General / Re: quality dense point cloud

« on: May 13, 2015, 09:40:47 PM »

I usually try different Point Cloud Density settings.  I had a mountainous forested scene with a flat grassy valley.  Ultra High might look great in valleys, but then poorly in the dense forests.  High may have few gaps, but then not as dense points.  Then I weigh the differences and see which one I prefer more.  Or split the project up and do the trees separately, then import them.  For flat areas, Ultra High has worked great, then I get a super high quality DTM/DSM.

36

General / Re: Camera calibration improving accuracy?

« on: April 30, 2015, 09:13:16 PM »

I calibrate our cameras in-house using the big dot wall.  I ran it both ways - with my camera info and letting Agisoft pick the interior orientation values.  Entering the camera calibration file into an Agisoft project and it did not improve the error results.  In fact, it was less accurate by 0.03 m (in the Error M and Error Pix columns).  I didn't do an accuracy assessment in ArcGIS though.  Letting Agisoft pick the interior orientation info was slightly better in the end. 

The only time I'd use that camera calibration info is if I created my mosaic in EnsoMosaic which needs it.

Someone asked me why I thought my calibrated camera info would improve results (I don't know it just seems like knowing exact data would be ideal, no?), but I was surprised.

37

General / Re: What does Optimize Cameras actually do?

« on: April 02, 2015, 12:57:33 AM »

I use the Optimze Cameras after I've aligned photos using flightlog location info, and added GPS aerial target coordinates to tie down my image even more.  I optimize and it changes the solution where I have to redo my point cloud based since it will be based on GPS targets instead of coarse flightlog data. 

But not sure how it's used if you don't have camera locations or GPS locations, hopefully someone can answer that here ...  (Just an example of how I use it.)

38

General / When to use Scale Bars; necessary to calibrate DEM?

« on: April 01, 2015, 11:41:00 PM »

I need some clarification on when I need to use scale bars in my mosaic products.

We have a UAV with GPS locations for each frame while captured in the air.  Then after alignment, etc, we have RTK GPS for aerial targets to finalize the mosaic (RGB, NIR, TIR).

Is it necessary to "calibrate" the DEM?  We are getting very good looking "ultra high" point clouds and the heights of vegetation seem to be believable (need ground truthing data to verify).  However, I'm unclear if we need to calibrate it, ie. enter the known height of a bush as a vertical scale bar in Agisoft or are the GPS targets enough?

Previously I thought that scale bars are only for when you want to make volumetric/surface area measurements and typically added as XY lengths.  If I'm stopping at a mosaic and DEM, do I need further steps?

I ask because we have a newly purchased laser tool for height/photo/GPS data of individual vegetation and wondered if that info could be used in Agisoft for anything.

Thanks.

39

General / Re: Computer Specifications

« on: March 04, 2015, 08:06:51 PM »

I am doing aerial imagery from a UAV, about 500 photos per project or less so far.

I have 32 GB RAM, 3GHz CPU, Nvidia GeForce GTX 760.  The RAM really gets maxed when I'm making ultra high point clouds.  They were looking to double my RAM.

40

General / Re: High accuracy without GPS

« on: February 13, 2015, 02:50:12 AM »

"If you are using survey grade GPS equipment (like a DGPS) and cannot get 15cm elevation"

To clarify, my vertical accuracy RMSE (when comparing the DEM to the actual Z) is not below 15cm.
The vertical accuracy of the points at time of collection is in mm using survey grade equipment.

Hopefully someone will know your answer.

41

General / Re: High accuracy without GPS

« on: February 12, 2015, 10:58:50 PM »

I don't even get 15 cm elevation accuracy WITH known control points using survey grade GPS equipment.

I just use XYZ of a control point.  I have not yet entered scaling differences or calculated differences between each elevation (not sure this is even required?).

42

General / Re: shapefile masks

« on: February 12, 2015, 10:54:40 PM »

Anyone?  I was just about to post this same question!

43

General / Re: Historic Aerial Imagery Advise

« on: February 03, 2015, 11:24:55 PM »

I am commenting to follow because I am about to start a very similar project.

I also found this post about historical imagery too:

http://www.agisoft.com/forum/index.php?topic=130.msg2764#msg2764

44

General / Re: Issue getting correct orhtomap

« on: January 30, 2015, 10:14:25 PM »

 n/a

45

General / Re: Issue getting correct orhtomap

« on: January 30, 2015, 02:08:29 AM »

You can hand select the points that are too low or too high to clean up that point cloud before you run the mesh and texture.  Only occasionally do I get a perfect point cloud that does not require any editing. 

You can also use the classify ground points tool so that the water tower is not included in your DEM creation (when you make mesh, change the point category).  This is what tutoss is saying.  It turns all the ground points brown (based on some settings you chose), then you make the mesh on ground points only.

If you do add ground control points, then you uncheck all your lat/long cameras or it will mess up the solution.  Also update the projection if you add control points.