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Messages - MurrayW

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General / Point Cloud height above ground
« on: March 18, 2019, 11:24:08 AM »

How can I assign height above ground to the MetaShape point cloud?  I have generated a dense point cloud. I have an accurate Lidar DTM. Can I assign DTM value to points? 

In Forestry, LAStools does a process called "normalize" where the ground elevation is subtracted from the Point Cloud elevation so the point cloud represents height above ground - which is the height of trees.  This is an essential step for forestry information from point clouds - can MetaShape produce normalised Point Cloud?


General / Dense Cloud Display colors
« on: February 27, 2019, 02:52:53 AM »

I have a dense point cloud derived from four band imagery. The point cloud is displayed as grey scale. The points have been colorized using Tools/Dense Cloud/Colorize dense cloud. I want to see the color of the points - Can the display of the point cloud be altered to show RGB color?


General / Re: Process four band images
« on: December 14, 2018, 03:18:45 AM »
Thanks Alexey.  That script works well.

Also, I have been learning about ImageMagick.

Here is some advice from experienced people:

"ImageMagick cannot write 4 channels to an RGB image using -combine. The fourth channel would be the alpha channel and it is added by -compose copy_opacity -composite. You can combine 4 channels as CMYK, if you want, but not RGB.

ImageMagick (6) does not write to multi-channel TIFF files right now as far as I know. It will write to multipage TIFF files by simply,

convert image1.tif image2.tif image3.tif image4.tif result.tif

See also ... php#define for -define tiff:alpha=associated|unassociated|unspecified for alpha specification"

General / Re: Mask Mesh build
« on: December 14, 2018, 03:14:03 AM »
Can resizing the bounding box be automated?

General / Mask Mesh build
« on: December 13, 2018, 05:37:58 AM »

I am using Photoscan for an aerial photo project. The triangulation results are good, I've created a dense point cloud.

I want to build a mesh and PS reports that it will take 3 days.  But, I only really need a small area.  How do I limit the mesh build to be only a selected area?

I have manually selected points from the dense point cloud using the Model/free-form selection tool, reversed the selection, and deleted those points.  That works, I do get a mesh limited to the area of interest. 

However, I cannot automate that process. 

Can Photoscan:

     - import a shapefile to select points from dense point cloud?
     - use a shapefile to constrain the area for mesh build?

or does someone have a better method?


General / Re: Process four band images
« on: December 07, 2018, 01:17:17 AM »
Hi Alexey,

I replied before checking the output images....

The output is 32 bit floating point, whereas the input was 16 bit unsigned integer. 16 bit is required.  So no success yet.

There is also an error message ! name 'doc' is not defined

General / Re: Process four band images
« on: December 06, 2018, 01:07:17 PM »
Hi again Alexey

I ran your script and it worked very well.  Processng speed was quick - much faster than ImageMagick.


General / Re: Process four band images
« on: December 06, 2018, 03:54:46 AM »
Hi Alexey,

If I start project with 3 band tiff for align cameras, GCP and optimize cameras, can Photoscan then substitute four band 4 band (png or tiff) in place of 3 band tiff?

I want to use RGB for locating GCP.  The GCP are painted "X"on ground in white paint and dGPS +/- 2.5 cm. GCP is very visible on RGB, but is difficult to see on single band gray scale.

Once optimisaton/triangulation has achieved desired accuracy, I can use "Change Paths" to subsitute four band imagery. Will dense point cloud, and orthomosaic, have four bands?


General / Re: Process four band images
« on: December 06, 2018, 01:14:31 AM »
Thanks Alexey

I searched for ImageMagick commands to write a tiff without the alpha band, but I did not find a solution.

I did use ImageMagick to write to .png format and in that case the alpha channel is in a separate file and can be deleted.   When reading the ImageMagick commentary on file formats, they do not recommend tiff, because of so many tags and different interpretations.

I will use png to test processing.


General / Re: Process four band images
« on: December 04, 2018, 12:26:43 AM »
Hi Alexey,

Can you tell me how to remove alpha mark ? Actually, I am not certain that there is an alpha mark.

ArcMAP does not show an alpha channel. Band 4 can be displayed - see attached screen grabs.  Also, I exported to 4 band tiff from ArcMAP and Photoscan can now see four bands.

Band 4 comes from a different camera, with simultaneous exposure.  But, overlap is not 100%, so band 4 has zeros on two sides. Perhaps this is why Photoscan sees Alpha channel?

Maybe TIFF means: "Thousands of Incompatible File Formats" .....   :-/

General / Re: Process four band images
« on: December 03, 2018, 06:51:07 AM »

General / Process four band images
« on: November 30, 2018, 10:23:32 AM »
Hi everyone,

i have some four band tiffs RGBI, and I want to produce four band orthomosaic and point clouds with RGBI colours.  Is this possible in PhotoScan? 

Is the process different to the RGB process?



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