Topics

1

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.

2

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.

3

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:

https://agisoft.freshdesk.com/support/solutions/articles/31000148381-micasense-altum-processing-workflow-including-reflectance-calibration-in-agisoft-metashape-professi

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?

4

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.

5

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?

6

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?

7

General / Analyze what is wrong with my historical aerial imagery mosaics

« on: December 08, 2015, 09:59:03 PM »

We are in the middle of a historical aerial imagery project where we scanned in paper maps at 1200 dpi.  No referenced data is known, but we pulled XYZ values from LiDAR bare earth and intensity rasters.

It's been a challenge to say the least adding the "right" arrangement of points without it blowing up. 

Anyway, some mosaics will turn out OK and others will have some issues (see attached). 

Is this mostly because I am using the standard DSM (aka all points) to create the mesh and not a DTM? It would be pretty impossible to classify ground points for a DTM with these forested scenes.  I've also been using the LOW or MEDIUM point cloud density quality so that I get a well distribution of points even up in the trees.  HIGH and ULTRA will leave lots of gaps which affects the mosaic.

8

General / "Speckles" in my thermal mosaic - not sure why this is going on

« on: August 12, 2015, 01:38:52 AM »

Camera: ICI 9000 Thermal Camera
640x860 pixels
AGL: 450m
16-bit stretching

We have used this camera before for TIR flights.  However, today I'm experienced some speckles in my final mosaic but not in the raw images.  Due to the TIR not working all the way to the end in Agisoft, I am importing the RGB model from this exact day/time/flight to make my TIR mosaic.  Great workaround, but these speckles are new for us.  Last year's TIR images were not put into 16-bit but rather 15-bit I think.  So a different stretching to the TIFs this year.

I've tried exporting various blending modes, enabling color correction.  These speckles are not visible on the raw TIR images.

Any ideas?

9

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...

10

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.

11

General / Best way to keep track of hours?

« on: January 29, 2015, 10:27:49 PM »

I often multitask and run more than one PhotoScan project.  I find it difficult to estimate the # of hours to complete a project (I don't count the actual processing time, just my interactive time).

Is there any tool/extension out there that will help me calculate my hours automatically?  Pen and paper is not cutting it.  Something if a window is front and active, a counter/tally will accumulate?  Then if it's in the background, it will not tally?  Mozilla Firefox has this for the internet usage.

Just curious how you might do that if you have to tally hours. 

12

General / Calculations/Formulas for Blending Modes & Pixel Upscaling?

« on: December 04, 2014, 09:02:52 PM »

First, I would like to know what the pixel calculations are for each of the blending modes:

Mosaic (default)
Average
Max Intensity
Min Intensity

Mainly the difference between the first two, but overall I just don't want to make any assumptions!



Secondly, when you export a mosaic or DEM and you increase pixel size, what "upscaling" method is it using?

13

General / Can I export the Image Overlap in Report? Or how about invididual frames?

« on: November 26, 2014, 10:11:08 PM »

Hello,

When generating a report after mosaicking, a graphic is in the PDF called "Fig. 1 camera locations and image overlap."

Is there a way to export to a raster or polygon for GIS? 
It would be so helpful and much easier than the other method I had in mind!

I am searching the forum and playing with the Tools | Export features, but not sure I'm getting it.

14

General / Using 3-band images, but output/mosaic is 1-band looking

« on: October 15, 2014, 12:30:30 AM »

I have 3-band RGB image about 783mb each TIFF flown at 1000m.  Unsure of sensor/camera.

I pulled in the TIFFs into Agisoft and created a mosaic using three of the images.  In the Agisoft view, the images still look good (aka RGB) even up to the texture step.

However, when I go to export the mosaic and pull it into ArcGIS, it has the picture clear in the red band, but the blue and green bands are just that - completely blue or green without any image even the zero pixels.  I have tried the Enable RGB color correction on and off, mosaic default, average, max, min - tiling too thinking maybe the mosaics were just too big.  No luck so now I'm asking the forum.

Here are some photos of what I'm seeing:

15

General / Advice on making my flat field "flat"

« on: September 10, 2014, 01:09:42 AM »

I am working with thermal imagery using a microbolometer thermal camera ICI 7640 (Infrared Cameras Incorporated).  Imagery was flown at 400 m AGL.  Images are 480 x 640 pixels.

My RGB and NIR point clouds came out wonderful for this flat vineyard project.  (see attached)

However, the two thermal flights are showing tons of bumps when I make the point clouds, or even random images that produce 90 degree "ramps" or "cliffs."

Here are the settings I'm trying:

Align photos:
I've tried high and medium accuracies
Pair Selection: Ground Control
Point limit: 1,000,000

Build Dense Cloud:
I've tried every combination I can think of
high, medium, low quality
mild, moderate, aggressive depth filtering
(not even totally sure when to use what still)

Build Mesh:
using Arbitrary for the surface type (since it's in temperature)
use high or moderate polygon count

See my various outputs below.  If I have one of those "ramped" or "cliffed" images, I try to find it and turn it off.  That does not help all the way.  If I try to delete those high points after I build a dense cloud (and before build mesh), then I have a hole in my imagery.

The issue is my end mosaics are very blurry in spots, only in the thermal.

Can someone help me improve what I'm doing?  Still new to this software.  These vineyard thermals seem to be a little more tricky than other thermal mosaics we've done.