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Messages - rossnixon

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General / Balancing dense cloud specs vs mesh specs
« on: August 17, 2018, 06:32:46 AM »
I was producing an orthophoto from about 260 aerial photos.
I ran out of memory creating the mesh from the dense cloud.
I lowered the mesh face count down to low (2.7 million), but still ran out of memory.
Then I disabled interpolation. This then worked.

1. What is the effective of disabling interpolation?
2(a). Should I have used Medium Quality, instead of High when building the dense cloud?
2(b). Would that affect how many faces the mesh could have?
2(c). If so, could I (somehow) thin down the dense cloud a certain amount?
3. What does Calculate vertex colors do; and does this take much memory?

General / Re: Photo Alignment Takes too much time
« on: August 07, 2018, 07:26:18 AM »
That may be fine if you don't have to do it very often.

I make do with i5 2500+ (overclocked), 16GB, onboard graphics!, and have processed 2000 photos in one chunk. Yes it did take a long time, but I only do this once per year.

General / Re: Ram usage on Orthomosiac stage
« on: July 06, 2018, 05:16:09 AM »
Before you get to the orthomosaic stage, you would have to build a mesh though. At an estimate, in your case you'd need about 800GB for that step. I base that on a Medium Quality model with 10,000 photos of 12 Mpx requiring 40GB.

General / Re: Problem with align of forested images
« on: June 21, 2018, 05:38:59 AM »

I'm working with forested areas, but the images not aligning. The flights that are in trouble were made at 60 meters of altitude and 80% of overlap, where only as border areas are recognizing homologous points. I made a new mapping at 70 m altitude and 90% overlap, where I got a better result but it is not 100% yet
We work with forested areas and get good alignment when flying about 6700 feet above ground. Using a Canon EOS 5D Mark II via a mount in a small aeroplane.

Bug Reports / Re: Export of Ortophotos
« on: June 12, 2018, 04:34:31 AM »
That is strange. I'm still getting orthophotos out from version 1.4.2.
This is for very small projects - only two or three photos in the job.

General / Re: about windows pagefile.sys file
« on: April 20, 2018, 04:21:54 AM »
"Not enough memory" refers to RAM.
The pagefile size probably has no effect on your problem. However, if your pagefile is getting extremely large for no apparent reason, you can set it to be a fixed size. Mine is set to 1GB.

General / Re: Optimize camera alignment creates larger errors
« on: March 02, 2018, 04:52:58 AM »
Images are fine. Only one of 0.69; the others average 0.80.

I usually use 40,000 key points & 10,000 tie points. On this job, those settings left me with 65 or 70 non-aligned photos. Setting to 0 (unlimited) made them all align.

I disabled all camera locations in the reference pane before running optimisation, as suggested.

Just now I tried the Gradual Selection process again. Last time I tried it, I backed out due to (at first glance) too many points being selected.

Options used this time: Reconstruction Uncertainty 10. Reprojection Error 0.75. Projection Accuracy 10. My sparse cloud has dropped from 3.1 million points to 200,000 points. Then I did Update & Optimize. The problem is now that optimization gave console messages: "removed 29 cameras", removed 29 stations", "removed 3 points".
My Z errors before decimation ranged from -1m to 13m. But now they range from -33m to 44m.
Perhaps I should be less aggressive with removing points in this case?

General / Re: Optimize camera alignment creates larger errors
« on: March 02, 2018, 01:28:57 AM »
Here is the report PDF.

My GCPs are based on an existing orthophoto with spatial accuracy is +-2m (@ 90% confidence). My Z values are estimated from 5m contours generated from LiDAR.

I have tried unchecking all cameras, but the Optimize Cameras process still makes the sparse cloud go haywire.
I had GCP 8 unchecked.

Perhaps I should run 'Model>Edit > Gradual Selection' before trying Optimize? I left that completely out as nearly all points were 'bad' - probably due to the big tree lean on the edge of photos (low altitude drone, wide angle lens).

My final orthophoto isn't positioned as well as I would like, but the tree lean is all gone.

General / Optimize camera alignment creates larger errors
« on: March 01, 2018, 06:14:52 AM »
Project is to make an orthophoto from DJI photos of a forest.
I aligned photos using the Reference option (longitude/latitude in EXIF).
To get all photos to align, I had to set Key Pt & Tie Pt options to 0.
I have 16 good precision GCPs, although I removed "8" as it had the biggest error.
A few photos had markers that I couldn't position due to tree lean/displacement, so I left those with grey symbol.

When I do Optimize Camera Alignment, my sparse cloud goes crazy, and my x,y,z errors get much worse. (The dialog box showed all options checked except Fit p3, Fit p4, rolling shutter.)

I have settled for creating the orthophoto without doing the optimize. It's not perfect, but still useable.
(Before optimize & after optimize (angled to show problem) images of sparse cloud are attached).

General / Re: Work Flow for GCP
« on: February 22, 2018, 01:19:22 AM »
3. Convert GPS coordinates of your geotagged images (WGS84) to match the coordinate system of your ground control points (GCPs) which will be imported later. Note that the altitude information stored in the EXIF data of imagery acquired by DJI drones is the relative altitude from the point of take off and not the absolute/real world altitude. Here are 3 ways to fix this issue:
I'm currently having a problem aligning a set of 500+ UAV photos over a forest.
Does the above step#3 mean than I need to somehow replace the longitude/latitude EXIF date with the coordinate system that my (very accurate) GCPs use? If so, how do I do that?
Also, is the altitude data used by Photoscan? Should I remove those?

General / Photo rotation before or after alignment?
« on: February 16, 2018, 07:53:14 AM »
I have many aerial photos. About half of them were taken at 180 degrees from the others.
The align photos process completed with everything aligned correctly.

But now I'm having trouble positioning my control points, so are having to rotate the photos inside Photoscan.
I think I will be able to get my errors down to acceptable levels. I haven't finished yet though.

Do I need to repeat the align photos process after this? I'm wondering if my tie point cloud is faulty and misleading, and will affect the final orthomosaic.

General / Re: Dimension Agsoft
« on: September 11, 2017, 01:29:38 PM »

Bug Reports / Re: geoid sign seems to be wrongly applied
« on: September 11, 2017, 01:27:29 PM »
I'm flying a DJI Mavic Pro and indeed it outputs what me may call "GPS altitude" but today I discovered that the height of the take off point I was using (in clear view of the sky with virtually no multipath) has "errors" of more ( :-[) than 100m between two flights separated 4 days, that is obviously unacceptable for photogrammetric processing.
I wonder if the bigger than expected altitude variation was caused by the recent CMEs and/or high level proton storm from the sun (but that was only in the past couple of days)?

General / Re: Export GeoTIFF, modify with Lightroom & than export to KMZ
« on: August 29, 2017, 12:54:15 AM »
See my post about creating hi-res KMZ files using G-Raster (very cheap).

General / Re: Orthomosiac aerial image exported as a kml file.
« on: July 10, 2017, 03:59:52 AM » You want G-Raster version 6.2, as there was a problem with 6.3.
It takes a geotiff or similar, makes it into a series of tiles, then packs it up as a single KMZ file.

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