Messages

16

General / Re: Dense Cloud Quality

« on: February 28, 2019, 06:43:48 PM »

 -Photo Resolution Scaling:  Alignment Quality-
Highest:        2:1
High:               1:1
Medium:       1:2
Low:                1:4
Lowest:         1:8


-Photo Resolution Scaling:  Dense Cloud Quality-
Ultra High:      1:1
High:                   1:2
Medium:           1:4
Low:                    1:8
Lowest:             1:16


Example: If Ultra high produces 100 million points, Medium quality will then create 25 million points.
If your project GSD is 2 cm/pixel, your maximum DEM resolution at Ultra high will be 2 cm/pixel. At Medium it will be 8 cm/pixel.

17

General / Re: inaccurate volume

« on: November 12, 2018, 06:40:15 PM »

If you have not scaled your project with either markers (GCPS) or a sale bar then your model will have *no* value other than looking pretty.

Photoscan has no idea what the size of the box is unless it's scaled. Otherwise it can be a box the size of ..a box, or a box the size of a house.

18

General / Re: Increase processing performance by a factor of 2

« on: November 06, 2018, 12:03:48 PM »

Interesting read. The first thing comes to mind; is the processed data (before you split it in 4 chunks) not still active in the cache or working memory?

When I'm running only one instance of PS I can see all of my cores being utilized, each and every time. And I definitely see a slowdown when running two unrelated projects simultaneously.

Curious to see what Agisoft has as an explanation.

19

General / Re: DJI Phantom 4 RTK

« on: October 18, 2018, 10:47:33 AM »

Regardless whether this particular RTK setup is stable or not - like 'aerial_survey' mentioned it's still mandatory to perform the measurements of control points scattered throughout your project site. If you have nothing to check your data against to it's pretty much useless from a surveyor perspective. In other words, you'll still be spending time walking around your project site and measuring points with RTK-GPS.

Furthermore it's interesting to think whether you'll even want to use RTK for the drone positioning and not just stick to PPK which has numerous advantages.

20

General / Re: Mesh VS DEM orthomosaic

« on: October 03, 2018, 12:06:32 PM »

In previous versions of Photoscan there was no option to create a DEM, only to create a Mesh. The Mesh and DEM are similar in that they are both models from the interpolated Dense Cloud. If you're unsure if you need a Mesh for your products simply stay with creating DEMs.

Using a DEM will sometimes yield better results when creating True Orthomosaics (an Orthomosaic based on a DEM and not a DTM) near building edges than using a mesh. This is because a DEM is interpolated using IDW whereas a Mesh is using linear interpolation to create a model.

21

General / Re: How does quality of dense cloud influence the resolution?

« on: October 03, 2018, 12:01:26 PM »

The DEM is a direct product from an interpolation of the dense point cloud.
If you've selected medium quality for the dense point cloud, you'll end up with a point density 4 times lower than is possible at the highest setting.
This means that the interpolated DEM will be of a lower resolution than your project GSD, which directly correlates to the used camera and flight altitude.

The Orthomosaic is generated by projecting the undistorted Ortho photos either onto the DEM or another available mesh surface. Since they are being projected, the resolution of the DEM (or surface) is irrelevant.

22

General / Re: Automate Bounding Box - Large Scene/Terrain

« on: September 07, 2018, 12:11:59 PM »

Hey Lauren_O,

That's quite simple. Once your images are aligned, go to the Toolbar > Tools > Reset Region.

This will re-align the bounding box ground plane (the red side of the bounding box) with the determined ground plane of the 3D model.

23

General / Re: Your opinion on USGS Agisoft Processing Workflow

« on: August 31, 2018, 05:31:26 PM »

Funny, seeing how I followed this workflow and got worse results than following our own developed workflow.

I suppose it all depends on your data set.

Could you outline your workflow and describe your type of data, out of interest?

Unfortunately I prefer not to go into depths of our workflow. I can say that it's quite different than what USGS following for their gradual selection filtering.
The results that the USGS workflow yielded were slightly worse absolute errors compared to independent check points than our own workflow and showed a decrease in the amount of detail for the dense cloud. Most likely due to larger misaligment errors compared to our own workflow.

24

General / Re: Balancing dense cloud specs vs mesh specs

« on: August 31, 2018, 05:29:06 PM »

Jwoods that's very much correct, unless Agisoft changed this parameter during an update.

If you're running out of RAM during the Build Mesh stage and you're unable to add more RAM or virtual memory then it'd best to duplicate the chunk (for safety) and rerun the dense cloud at a lower quality level. From what I remember, going down one step in the quality level means a factor 4 reduction of generated dense points. With this info you can get a rough sense of the amount points you'll end up with after the dense cloud stage.

25

General / Re: HELP to Build new Computer

« on: August 31, 2018, 05:21:03 PM »

The question that's on everyone's lips is *how* well will all those 32 cores scale for software like Photoscan.
More core does not necessarily mean less computation time if the software is not optimized for it.

I'll wait for the benchmarks to show up. In this world, benchmarks and serious comparisons speak louder than opinions.

Hey Alvaro L,

I remember this post of you. It made me laugh, why? Because I already knew beforehand that simply adding more cores will not mean better performance. This has been proven time and time again.
This goes for Agisoft Photoscan, Pix4D, Bentley ContextCapture, CAD software..any software really.
This does not mean that performance can't get better over time when updates are implemented but this is to be seen.

Now you're of course curious for the proof. Welp here it is;

https://www.pugetsystems.com/labs/articles/Pix4D-CPU-Comparison-Coffee-Lake-vs-Skylake-X-vs-Threadripper-1084/#Results

26

General / Re: Your opinion on USGS Agisoft Processing Workflow

« on: August 31, 2018, 11:55:26 AM »

Oh Geeze, the results after using USGS methodology are 100x better than not.
This should be part of the agisoft standard workflow IMO.

I wonder if the gradual selection steps could be automated. I am a .net guy mainly but can adapt to other languages.
I sent my "re-write" of the USGS workflow to agisoft sales. Hope they do something with it.
In the end, the PS results were better than Dronedeploy and pix4d.

Funny, seeing how I followed this workflow and got worse results than following our own developed workflow.

I suppose it all depends on your data set.

27

General / Re: DEM from Mesh not dense cloud

« on: August 08, 2018, 01:22:03 PM »

Any alterations made by Photoscan when generating the mesh from the dense cloud will bring these changes to the derived DEM from the mesh as well. Therefor it's prefered to do it straight from the dense cloud.
However your approach by manually cleaning some geometry and or vegetation from the mesh and then using this as a basis for the DEM is not a bad approach as you have a bit more control over how your DEM (DTM in this case) will look like.

When generating the DEM you can select which point classifications it should use during interpolation. When you've classified your points through auto classification or manual you can use this classification. You can set this up in the Build DEM window when pressing on the select button at 'Point classes'.

28

General / Re: Exported textured .obj model quality loss

« on: August 08, 2018, 01:13:51 PM »

AFAIK this has to do with the visualization settings of MeshLab. Try playing with the different shading and lighting settings of Meshlab.

29

General / Re: HELP to Build new Computer

« on: August 01, 2018, 09:00:41 PM »

I'll speak to you in a year once your tears dry up over your purchase mistakes, lol.

30

General / Re: Export DEM (.TIF) for importing in Civil 3D

« on: August 01, 2018, 03:27:33 PM »

Hey Bob,

How did you import the TIFF into Civil 3D? Did you use the XREF function? See: https://forums.autodesk.com/t5/civil-3d-forum/insert-raster-image/td-p/4878368

As for the file size difference between QGIS and Photoscan;  Photoscan uses LZW lossless compression on the TIFF file which greatly reduces the file size without data loss. I'm uncertain that QGIS also does this by default.

When using GlobalMapper to export TIFFs you'll notice a huge difference in file size if you enable or disable LZW compression. I'd advice to use the compression as this usually means less loading times when importing into a GIS.