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 ... 7
General / Re: DEM from multiple flights - seam artifacts?
« on: September 22, 2022, 12:07:27 AM »
When we do projects where there are several flights to merge together, there has to be a ground control point in that overlapping area that is shared between FL1 and FL2. Otherwise we'll get this difference in elevations, just due to the error of the GPS on board the UAV.

Maybe you can make up a ground control point, using an available DEM and a high resolution basemap (other satellite imagery). It needs to be tied down.

General / Classify Ground Points - multiple orchards of different growth
« on: September 22, 2022, 12:05:23 AM »
I am trying to classify the ground between trees of an orchard. We've done it successfully on vineyards before with satisfactory results, but the entire scene was quite uniform - vines of similar ages.

This new project has orchards of different growths (young to mature).

What are the chances one set of parameters (max angle, max distance, cell size) are going to be suitable for the entire scene? I'm going through a gazillion iterations the past week and not liking any of them.

General / Calculating extra bands in Raster Calc then Exporting Ortho
« on: July 15, 2020, 03:33:16 AM »
I have a 6 band Altum Micasense camera. I want to tack on a bunch of extra index calculations so I don't have to do this in ArcGIS.

Bands 1-5 are the visual converted to reflectance
Band 6 is thermal converted to Celsius
Bands 7-12 are my extra calculated bands

I want a 12 band raster with all those calculated bands. I know that "Index Value" in the Export Ortho is how you activate the calculations, but the resulting image is totally grey.

Index Color is for the Palette, checking "Enable Transform" gives only 3 bands. None in Export Ortho gives the original 6 bands.

What is the trick to get all 12 bands with the calculations in the Raster Calculator performed?

I am able to export a raster with the first 6 bands in my list (the normal Altum bands), and a separate raster with the last 6 bands (my 6 bonus calculated bands) just fine, but not all of them together without being grey.

Thank you Paulo! I will say to the client that the TIR has been upscaled to match the other bands.

Micasense shared a bunch of GitHub links today that have the explanation somewhere in there. I didn't know these existed until I made a help ticket with them.


Can I actually report to my client that the TIR has a 5cm pixel resolution?

It is documented that the TIR resolution/GSD is going to be much more coarse (80cm on the Altum specs sheet). Hence the confusion on what to report.

General / Micasense Altum Thermal: conversion, resolution questions
« on: May 27, 2020, 11:47:08 PM »
We are flying the Altum camera at 400ft AGL.

An Agisoft project was created using all 6 bands as in the instructions link:

I am experimenting with different ways to convert the thermal band into Cel, ie, Agisoft's Raster Calculator, ArcGIS's Raster Calculator.

In the 6-band Agisoft project (after the 5-band relfectance was exported),  removed the lines with B1/32768; B2/32768; B3/32768; B4/32768; B5/32768 lines, and replaced it with a single line: (B6/100) - 275.13. I've exported the ortho (Index Value selected). Then also another thermal raster where it only said B6 in one line, and did the calculation to Cel in ArcGIS Raster Calculator. Just to compare. Values were same. Good.

Both resulting thermal images from the original 6-band Agisoft project have super fine resolution of 5cm (same for the BRGNIRVRE bands). I am not sure what it's doing to the thermal, upscaling? Can anyone explain?

Then I created a new Agisoft project, but only using the Altum thermal images. This final raster had a 69cm pixel resolution, closer to the 80cm that Micasense reports for a 400ft flight. I also tried to find the difference between my 69cm thermal raster and 5cm thermal raster. While not apples to apples, or a perfect comparison, there were some bigger numbers than we were expecting.

Can anyone tell me how Agisoft is processing the thermal band when it's part of the 6-band multicamera project and why it makes the resolution much finer?

Also those with the Altum, which software do you prefer to convert your centiKelvins to Cel?

General / Re: Exporting large orthomosaics
« on: December 01, 2018, 12:00:36 AM »
Does checking the "Write BigTIFF file" in the Export Ortho window work for your purposes? I've exported 50GB mosaics in one piece this way, but I use ArcGIS to view the images. I've used Split in Blocks as well (you'll have to play with the pixel sizing, I've used 5000 or 10,000).

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.

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.

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.

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.

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

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?

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?

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.

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?

Pages: [1] 2 3 ... 7