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Topics - AndyC

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General / Clarify confidence intervals of accuracy terms?
« on: January 15, 2020, 02:06:19 PM »
Could anyone from Agisoft clarify the intended confidence intervals of the 'accuracy' terms for camera and marker geolocations?

(some users seem to assume that these are 1 sigma (68% confidence interval), while others consider them to be 2 sigma (95% confidence interval)).

Python and Java API / How to add 'description' string to orthomosaic export?
« on: September 04, 2018, 03:15:21 PM »
We would like to add a string text to the 'description' field in the tiff metadata when exporting orthomosaic tiffs, (in order to facilitate data management).

Adding strings to the description field is available when exporting orthomosaics via Batch Process in the GUI, but we have not been able to implement this in our Python scripts, and this is not described in the API.

Can anyone offer examples of the arguments to include descriptions in orthomosaic exports?

Any suggestions much appreciated,

Feature Requests / Differently scaled exports from raster calculator
« on: August 17, 2018, 12:46:24 PM »
We would like to be able to export the outputs of the raster calculator with the direct values, rather than rescaled values.

For example, when using the raster calculator we generate NDVI maps with attribute values ranging from +1 to -0. However, when we export these reflectance maps (e.g. as tif files), the attribute values are rescaled to 0-255. We then have to load these maps into another software to rescale them back to -1 to +1. It would be nice to be able to export the files we need directly from PhotoScan.

Andy & Dave

General / Slow dense cloud generation with Tesla K80 GPUs
« on: August 17, 2018, 12:35:56 PM »
We are encountering unexpectedly slow dense cloud generation on a high-performance cluster. Any help working out the solution would be greatly appreciated!

We have two computer systems:

Workstation: (OS Windows 64; CPU i7-7800X 6-core 3.5 GHz; GPU 1 x  NVIDIA GeForce GTX1080; RAM 128GB DDR4 2133 MHz; Photoscan-Pro 1.4.2 build 6205)

Cluster: (OS Linex; CPU 2x Intel Haswell E5-2640v3 16-core 2.6GHz; GPU 4x NVIDIA Tesla K80; RAM 256 GB DDR4; Photoscan-Pro/1.4.3)

Our test job consists of 489 x 20 MP photos, processed through the initial steps (alignment, precise markers, tie point filtering, optimisation, etc.). All available GPUs are enabled on both systems (x1 on the workstation, x4 on the cluster; either via the GUI or with " = 2 ** len( - 1  # activate all available GPUs"). We will be using Python scripts for (mostly) headless processing. Dense Cloud Generation was attempted at ultrahigh quality with mild depth filtering on both systems.

On the workstation, depth map generation takes 9 hours and dense cloud generation takes 28 hours (37 hours total).
On the cluster, depth map generation takes 5 hours and dense cloud generation takes >28 hours (not complete after 33 hours).

(We thought that there might be unexpected overheads with using the 4 GPUs on the cluster, but our tests with 10 and 100 image sets show processing time consistently decreases (slightly) as the number of GPUs increases).

(1) Would anyone comment on our expectation that this Cluster should complete dense cloud processing substantially (e.g. more than 40%) faster than this Workstation?

(2) Could there be an issue with the GPU not being configured for optimal performance from PhotoScan?
(e.g. the compute mode, as hinted at by Alexey here

We have no experience configuring GPUs, but suggestions are welcome, especially if it might be possible to better optimise the K80s via the Python script.

Bug Reports / (Minor) Issue with Exporting Point Clouds
« on: March 13, 2016, 02:08:57 PM »
I've noticed a minor interface issue when exporting point clouds from PS v1.2.3_2331. In the Export Points tool, when selecting source data, the drop down options are 'sparse' or 'dense' clouds; however, once selected, these descriptors are replaced with either 'yes' or 'no', which are somewhat ambiguous. It would be useful to change this to display 'sparse' or 'dense' once selected.

Only a very minor issue, but hopefully it will help continue making PS even more accessible to new users.
Cheers, Andy

General / Understanding Image Residuals
« on: January 28, 2016, 08:22:15 PM »
Please can anyone clarify exactly what the image residuals presented in the camera calibration section of the processing report indicate?

I believe it is (1) the amount of distortion (error) corrected by the lens model. However, I was also wondering whether it might instead be (2) the amount of distortion (error) that remains uncorrected after the lens model was applied?

(Apologies if this has already been answered elsewhere, I wasn't able to find this explained)

General / Defining precise bounding box (before dense reconstruction)
« on: November 14, 2014, 02:09:34 PM »
Is there any way to use XY coordinates to define the reconstruction volume bounding box precisely, rather than visually?

I guess one roundabout approach is adding additional markers with the desired coordinates at each corner and zooming in to set the bounding box visually, but I was wondering if there might be a neater approach?

Thanks, Andy

Feature Requests / Reporting information on reconstruction processing
« on: November 14, 2014, 01:05:26 PM »
When generating reconstruction processing reports, I think it might be helpful to include the project file name in the report (facilitating version tracking when working with multiple projects), and add an option to also include the 'chunk info' (parameters used for each processing step and maybe processing times) in the default report?

General / Selecting Data Layout when Importing Photos?
« on: October 08, 2014, 01:46:46 AM »

When adding photos to a project, if I select the 'Add Folder' option PhotoScan presents a choice of Data Layout, allowing the imagery to be loaded either as (i) individual 'cameras', or (ii) one multiframe camera.

What is the difference between these options? (I would guess that it determines whether the camera intrinsic parameters are allowed to vary between each image or whether the same derived parameters are applied to the entire data set; but I don't know whether this is correct?)

When is each option is best; is the 'multiframe camera option intended for when using a high quality camera with a prime lens? (I'm processing imagery obtained using a nonmetric consumer camera, so it's conceivable some of the lens elements may have shifted very slightly over the course of several hundred frames).

Thanks, Andy

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