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Topics - WSurvey

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General / How do I extract DEM elevations at specific coordinates?
« on: June 18, 2019, 01:35:24 PM »

Given a text  file of E,N or X,Y or Lat,Long horizontal coordinates, is there any way to automatically extract the DEM elevations at these locations? Perhaps a way to import points and set them on the DEM and export again?


Feature Requests / Centre of weight detection for placing or moving markers
« on: February 16, 2019, 08:58:54 AM »
It sure would please me to be able to place or move targets to the calculated centre of weight of a white-on-black or black-on-white dot. Drawing a circle around the region then have the software add or move a marker to the centre would be a bonus for situations where automatic detection just won’t cut it.

Or even better a snap-type of mode could be enabled whereby if a marker is moved then it snaps to the greyscale centre of mass of the surrounding 4, 9, 16 or whatever amount of cells you specify as a tolerance.

General / GPS INS/Offset direction?
« on: October 03, 2018, 05:08:06 PM »

Pardon me if this question has an obvious answer, but is the GPS/INS offset from camera to GPS unit or GPS unit to camera?

I didn't find the answer in the documentation for whatever reason.

If my GPS unit is mounted 0.25m above he camera centre, is the offset I should enter +0.25 or -0.25?


General / Ideal shape for feature point detection?
« on: August 06, 2018, 05:22:56 PM »

What, specifically, is the ideal shape, size and composition of a feature point that Photoscan is looking for?

If I was wanting to print off some artificial textures from my laser printer for close-range photogrammetry that would be perfect for feature point detection, what would the texture look like? How big in pixels? Soft or sharp edges? Dark marks on light background or light marks on dark background?


General / Dense Cloud - Where do the rings come from?
« on: July 21, 2018, 01:00:18 PM »

Attached is an example of a dense cloud generated using 2 x 20 Mpx photos from a P4 Pro. An accurate camera calibration is in use and they are part of a larger set. Relative position and orientation should not be a problem.

Why do the rings appear? They change in number and amplitude depending on the settings but are always there.

General / Limitations of camera distortion model???
« on: July 01, 2018, 03:46:47 PM »

I have noticed that towards the edge of my dense clouds, where the cloud seems to have been created using a small number of photo-pairs (only 2 perhaps) there occurs a ripple type effect. I'm noticing the same effect in my camera calibration residuals. I'm processing aerial photography from a Phantom 4 Advanced, 20Mpx camera. There are a good number of survey-grade markers in my area of interest and this occurs no matter how many parameters are solved for in the camera distortion model.

Could this be an effect or limitation of the camera model, or in the generation of the depth maps, or something I'm missing in my own techniques?

Screen caps attached.

General / is CPU speed/core-count important for GPU processing?
« on: January 31, 2018, 05:18:51 AM »
The following question only pertains to GPU accelerated processes: Once you have the GPU handling the heavy lifting, does it really matter what kind of CPU is feeding the GPU?

for example, is an i3-2100 able to adequately feed a GTX 1050Ti all the instructions that it needs to be working at max capacity? would having an i7-3770 feeding the same card make much difference at all for the same computational problem?

General / More GPU's or more nodes?
« on: March 09, 2017, 01:35:31 AM »

Cost aside, if one wanted to decrease processing times for aligning photos and building dense clouds, or any time consuming operations, would one go about getting more licences to run network processing or start throwing more graphics cards at the problem? Assuming each extra computer has useless (integrated) graphics but good core i7 processor.

Also second question. I'm processing on an i7-3770 with 16Gb and no graphics card (just motherboard integrated GPU) and that's the best I've got in my office. Am I missing out on much speed by not having a good, single, stand-alone graphics card like GTX 970?


General / Too much wasted geometry
« on: March 03, 2017, 01:49:49 AM »

I am trying to make reasonably sized 3D PDF models of various sites for a client. The PDF has to be reasonably sized to be able to be displayed and rotated smoothly on ordinary computers. So I need the sites to be faithfully modelled with as few triangles as possible. Trees and building rooves are in the scene and no matter the final polygon count you specify they take up too high a percentage of the polygon count because of the roughness of their surfaces. Then the rest of the site is poorly modeled.

Rather than extensive editing by hand, are there any processing or filtering strategies that will serve my needs? I need a more uniform distribution of triangles. Not 1000's of triangles just to model tree tops and rooves.


Feature Requests / Marker Refinement
« on: March 02, 2017, 06:08:31 AM »
Once a marker is placed in a photo it seems it's intersection with a surface is used to approximately place markers in other photos. Sometimes the surface is not so good and the markers are placed well away from where they will end up. Ideally, once a marker is positively placed in two or more photos the rest of the markers should update their positions as we now have a reliable intersection with which to estimate the location of the remaining markers. This would speed up the process of moving markers to their final locations in larger image sets.

Excuse the post please if there is already a way to do this, but I cannot find it.

General / Extract point coordinates?
« on: February 22, 2017, 02:30:58 AM »

Say I have created a project and georeferenced it. It is now in my job coordinate system, and I notice a point of interest that I would like real world coordinates for. If the point does not lay on the surface I have created in the project is there any way I can identify this point in a few photos and extract the intersected coordinates? Things like roof corners, tops of power poles or any other unique points that do not lay on a surface.


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