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Messages - pbourke

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1
General / Aligning chunks
« on: June 04, 2019, 06:25:18 AM »
A question about aligning chunks.
I'm scanning lots of objects in halves, top and bottom. Generally I do both halves all the way through to textured meshes, identify markers in each, align and merge ... all good.
But I'm curious what the align option by point is for. Doesn't ever seem to do anything, what circumstances is it for?

2
General / Re: too many pictures
« on: June 04, 2019, 06:13:25 AM »
Easy enough to do outside MetaShape, assuming your photos are evenly distributed and have a unique continuous counting id ... for every second image simple make a new directory and
     cp *.0 *.2 *.4 *.6 *.8 ../newdir
Or the equivalent for your file numbering scheme and OS.

3
General / Crazy textures
« on: June 04, 2019, 06:09:02 AM »
MetaShape often/usually creates "messy" textures maps, made up of lots of different pieces, and clearly quite inefficient use of the image area. Is there a way within MetaShape to reorganise the UV coordinates (and hence the texture map) into something more continuous? If not within MetaShape, what is a (simple) external tool for this?

4
General / Re: Unexpected results
« on: June 04, 2019, 06:05:51 AM »
When I set point alignment accuracy to "highest" then all seems fine, except for the time it takes. :-)

5
General / Masks
« on: June 04, 2019, 06:04:47 AM »
When using masks what are some examples of when one should apply masks to key points or tie points?

6
General / Re: Unexpected results
« on: June 03, 2019, 09:43:59 AM »
Just a further comment to say I am aware of the depth of focus issues. I rotate the specimen around in 20 degree steps and focus on either the forward rim or the back rim, I do this for 3,4,5 heights depending on the object geometry. I imagine there is lots of in focus areas between the adjacent images and between the heights.

7
General / Unexpected results
« on: June 03, 2019, 09:36:37 AM »
I'm a long time PhotoScan / MetaShape user.
I've started a project scanning small objects, around 1cm-2cm on their longest axis. For this I am using the Canon MP-E65mm 1:1 to 1.5 macro lens, but mostly using between 1:1 to 1:2 magnification.
The first few worked (eventually) but if they work seems a bit random despite not changing my protocol. I am doing the objects in two halves, lots of overlap and merge by markers. I do not touch the lens after I start, focus is manual on a slider rail.
I am using a motorised platter in a light box and I mask all images.
I set photo-invariant parameters to all, lens characteristics don't change.
I set camera calibration to auto and adaptive cameras in photo alignment.
The first few worked fine, but in the latest batch 2 do not, despite me not doing anything different (that I know).
See typical screen shots after photo alignment, lots of keypoints. The camera positions are 90% correct but not all, in the attached there are some cameras on the right incorrectly assigned to near the top.
Ideas on how to configure MetaShape options for this type of work?

8
General / Re: size of the 3d model
« on: April 17, 2019, 06:47:50 AM »
My approaches
1. Use scale rules and therefore create a scale model in MetaShape. See attached.
2. Export as is, scale in external  software to a known/measured dimension.
3. Export as is, scale to unit cube bounding box and apply real scale in viewing software.
I use meshlab for 2 and 3.

9
General / Comment/bug about forum attachements
« on: April 17, 2019, 06:44:53 AM »
I mentioned this before but it hasn't been fixed.
When replying to a forum question if I attach an image that is too large I get the error "attachment greater than 768kb". If I scale the image to under 768 and repeat, I then get the error "attachment greatre than 512".
Rather annoying and time waster when one is only trying to assist others in the forums.

10
General / Re: How to delete part of the dense model
« on: April 17, 2019, 06:31:37 AM »
Standard way to delete dense point cloud is using the tools as shown in the attached.
Common pipeline is to clean dense cloud before meshing.

11
General / Lens question
« on: April 17, 2019, 06:12:29 AM »
I have a large number of small objects to be reconstructed.
I've done a few using the Canon 100mm but that is a 1:1 lens and only works well for objects down to 2cm long, on a full frame sensor.
I would like to know whether 1:2 or 1:5 lenses can be used. For example the Laowa 60mm or Canon EP-E 65mm, see
     https://www.venuslens.net/product/laowa-60mm-f2/
and
     https://www.canon.com.au/camera-lenses/mp-e65mm-f-2-8-1-5x-macro
This is where my knowledge of optics and relation to MetaShape are deficient. They are both a single focal length, but can zoom from infinity to close range, and I believe the image size changes significantly during focus.
Anyone understand this stuff?

12
A couple of comments

- I wouldn't worry about the GPU, my understanding is it won't make any difference from a model quality perspective, only the time taken.

- With regard to the quality of the results, what are you trying to reconstruct? There are well known/understood problem cases. For example smooth featureless surfaces, highly specular or reflective surfaces.

- And lastly and more speculative .... I've had mixed success with mobile phones. One of the issues I imagine is that phones these days are doing all sorts of processing on the images, often without you knowing or being able to do anything about it. I wonder if this processing which can include global changes can degrade coherence of what would otherwise be good across image feature points. Even with my DLSR capture I turn image processing/enhancements (or whatever the particular manufacturer calls it) off.

13
General / Masks
« on: March 14, 2019, 05:42:23 AM »
Can I have some suggestions on when one chooses to apply masks to keypoints or tiepoints?

14
General / Re: Can I edit Texture?
« on: March 14, 2019, 04:16:55 AM »
I always do it external (manually) to MetaShape, of course sometimes the texture is easier to edit than other times.

15
Feature Requests / Save chunk views
« on: March 14, 2019, 04:00:55 AM »
It would be most helpful for the last view of a chunk were saved with the chunk.
A time waster at the moment when I switch between chunks and the camera view of the chunk I'm switching from is used instead of the camera view from the last time I viewed the new chunk. I need to continually realign/reposition the camera ... switching between chunks is a fairly common exercise during manual marker placement.

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