Forum

Show Posts

This section allows you to view all posts made by this member. Note that you can only see posts made in areas you currently have access to.


Messages - aggieair

Pages: 1 [2] 3 4 ... 7
16
General / Re: Process four band images
« on: November 30, 2018, 11:57:01 PM »
We often work with TIFs that have 6 bands and also more than one camera with multiple bands.  The point cloud would only represent the first three bands I believe ??, but the ortho will have all the bands.

17
General / Re: Which is the best workflow to create thermal orthomosaics?
« on: December 23, 2017, 02:54:59 AM »
We use ICI thermal cameras and make thermal mosaics.

Align
Add GCP (we made targets out of 2 emergency space blankets and a visual target on top)
(I have build dense point cloud and ran my mosaics with and without it, prior to adding the mesh, sometimes it made it better other times it did not - just depends, I use aggressive rarely the milk or moderate)
Import RGB Mesh (if you have an RGB flight)
Build DEM (arbitrary since our Z field is not height, but temperature)
Build Ortho (average blending mode is better than mosaic blending mode for us)

Normally we have a corresponding RGB flight that I export its model/mesh to use as a surface in the thermal. The only time I did not is when the thermal flight is pretty low 30 m AGL for example.

18
General / Accuracies excpected for Historical Aerial Imagery DEMs?
« on: March 15, 2016, 10:41:45 PM »
For those of you who have used scanned historical aerial imagery to create mosaics and surface models, can you share what kind of vertical accuracies you achieved and what were you data sources?

We have both black & white and color scanned images (at 1200 dpi) from 1948-2004.  I did not remove the fiducials/borders, so the image size extends to the end of the photo (this didn't pose too much of an issue actually).  I have no interior orientation info either.

For GCP markers, we pulled horizontal locations from a NAIP 1 meter resolution basemap, and vertical info from a LiDAR raster.  Finding points was definitely trick as this was Washington state where lots of clear cutting occurs so every year looks different, but we were able to find some control points.

Then we compared our DSM created from Agisoft to the existing LiDAR (ideally flat ground and avoiding the surface of the trees), and it's a pretty large difference.  Yes, we were kind of limited to the center of the images as the sides were super forested and steep inclines.  Depending on the scale (1:4800 and 1:1200), vertical ranged from 3 to 9 feet and horizontal ranged from 9 to 18 feet.

Just wanting to know if our results are as as good as expected or if getting RTK GPS would improve things.  I'm thinking not that much given the challenge of finding fixed features to go out and GPS that would be in our historical imagery and also the type of terrain so we're limited on how well to disperse the markers in the scenes.

19
Yes, it as helped our projects greatly being able to include yw, pitch, roll now in the current Agisoft version.

20
General / Re: What causes these random bubbles/disks in point cloud?
« on: January 16, 2016, 01:00:20 AM »

Hello aggieair,

Such artifacts  are usually related to the misaligned cameras in the given area. For example, when the images from the overlapping flight lines do not have any matching points but cover the same area. So usually it is a result of alignment problems.

Would trying out various Align values help this?  Or given the set of imagery (assuming you can't refly) there is no way to improve things?

21
General / What causes these random bubbles/disks in point cloud?
« on: January 15, 2016, 01:38:10 AM »
Sometimes I get these circular bubbles/disks in my point cloud.  Almost looks like frozen bubbles in a lake.  I generally leave them be as the rest of the image is pretty good.

Any idea what causes this issue?  This area has overlap from two flightlines (the two flightlines make almost an X in this area).  However I've seen it on straight flghtlines that appear to have decent overlap.

Do you get this issue?  If so, how to you fix it?

22
General / Re: Actual photo overlap and Report photo overlap - different?
« on: December 16, 2015, 01:37:21 AM »
Agisoft checked it out and said "It seems that the issue has been related to the feet used as geographic coordinate system units. Will add the fix to the next version update" in case anyone was following or will look this up later.

23
General / Re: Actual photo overlap and Report photo overlap - different?
« on: December 11, 2015, 02:59:27 AM »
Ok, this is interesting.

I already had an old .psz project for this same project (this is before I was aware of the version upgrade).  Version 1.6.X something.

WHen I learned of the newer Agisoft version, I opened this old .psz and saved as .psx.  The outputs from that .psx are what I posted in the original post.

Attached in this post is the report image overlap I made from that old .psz project where I the mosaic was mesh-derived, not dem-derived.

So it cares if the mosaic is made from the mesh to get a proper overlap image?

24
General / Re: Single image ortho rectification
« on: December 11, 2015, 01:27:11 AM »
Based on my year experience so far, I'm going to say no because when I put down a marker/GCP, it must exist in two frames at least.  If it's in one frame, then it doesn't even get considered in the solution. (PS I work with only aerial imagery)

25
General / Re: Actual photo overlap and Report photo overlap - different?
« on: December 10, 2015, 11:27:06 PM »
Hi Alexey, didn't think you'd be awake!

Yes a Mesh was generated for this project (and all projects, this was before I knew about the DEM-derived option in 1.2.0).  I believe it is complete, but otherwise how is that indicated?  Used HIGH face count on a LOW dense cloud.

I did however, continue this project (after the software upgrade) with the Build DEM and Build Orthomosaic options, but it hung on to the Mesh from the original version.

UPDATE: just reran the mesh (just in case) and made another report.  Same result.

26
General / Re: orthomosaic coloration problems
« on: December 10, 2015, 09:43:15 PM »
Which blending mode are you using?  I typically use Mosaic all the time.

From Agisoft:

    Mosaic (default)
– images are decomposed into high frequency and low frequency components. A weighted average is calculated separately for low frequency and high frequency components (with different weights), which are subsequently combined back into final image.
    Average – simple weighted average of overlapping image colors.
    Max Intensity – color from the image with the highest intensity at the corresponding point is used (without any changes).
    Min Intensity – color from the image with the lowest intensity at the corresponding point is used (without any changes).

27
General / Actual photo overlap and Report photo overlap - different?
« on: December 10, 2015, 09:41:13 PM »
Normally we are used to projects with planned UAV flights and recorded flight log info.

Currently I'm on a historical aerial imagery project.  Images were scanned at 1200 dpi on a large format reflective scanner.  No flight log or orientation info was include - purely paper maps only. Markers were extracted from LiDAR information for orthorectification.

See my attached photos.  Laying the images out on the floor shows decent overlap.  The point cloud is decent and it makes a decent looking mosaic in ArcGIS.

However, in the report PDF, it looks like awful overlap and an awful mosaic.  Any reason to this?  I need to assess 24 individual projects for overlap success and was hoping to just glance at the PDF report rather than laying out hundreds of images all over again.  Agisoft projects have been started for all a generating a report is possible.  I just want to be sure its reporting it correctly.

Can anyone clarify this?

28
Yes, much better!  No more shards of glass issues :)

When zoomed to full extent in ArcGIS, the new DEM derived mosaics appear "softer" or not as sharp as the previous mesh-derived mosaics.  But then upon zooming in and checking the pixel size, they are nearly the same.

Sorry I have not made any dense point cloud screen shots for you yet...

I am working on comparing the new DSM rasters now derived from point clouds...

We were just about the export the points to Global Mapper and to this externally. Phew!

29
From Agisoft:

The issues that you are observing on the orthomosaic might be related to the low number of polygons in the area of interest. Even when you are using High face cont option, the could be areas with small polygons (related to the trees and greenery, for example) and big polygons (on the roads or bare ground).

Additionally we would like to inform you that version 1.2.0 has been released recently and it allows to generate DEM based on the dense cloud itself, so the issues the large polygons can be avoided:
http://www.agisoft.com/downloads/installer/


This was the trick.  We were just about to create the mosaics in an external software using the LAS points as a last resort.  Now it can be done in Agisoft!

30
General / Re: Problem with aligning photos
« on: December 08, 2015, 10:00:59 PM »
If mine don't all align on the magic 40000,10000 starting point, then I need to fiddle with the values a lot.  I also align on high unless I'm making a quickie mosaic.  Always use reference as pair selection if your images have lat long data.

Pages: 1 [2] 3 4 ... 7