Image projection

Support and discussion of Thinkbox Software's Point Cloud Meshing tool.
totte921
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Joined: Wed May 03, 2017 8:32 am

Image projection

Postby totte921 » Wed May 03, 2017 10:06 am

Hi, i'm trying to project a panorama image on a point cloud i Sequoia but the result is very bad. The point-alignment tool doesn't positioning the image
particularly good and now I'm trying to adjust the projection manually by rotating/translating the view and changes the UV-offset parameters but it's takes very long time to get it good. I wonder if my projcetion picture perhaps is in wrong format. I created it in PTgui as a cylidrical image from 4 images, that was rotated 90 degrees for ecah shoot with a 180-fish eye lense:
Image

As you can see I can rotate the image projection for the building in the background but then the projection becomes wrong for the building to the left.
Image

What kind of images are proposed for this type of projections? Spherical or Cylindrical? 360 degree Fov or 180 degree Fov ? How do I know how much I should change the UV-offset and UV-scales? Do I have to take the photographs from the exact same position as the laser scanner was placed?

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Bobo
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Re: Image projection

Postby Bobo » Wed May 03, 2017 1:34 pm

Hi!

Unfortunately, Sequoia does not currently support the Cylindrical projection you are trying to use.

Would it be possible to produce an Equirectangular (LatLong) projection from the PTgui? I know you don't have the top and bottom views, but if you could make a LatLong projection with the top and bottom missing (black), you could use the Sequoia Panorama mode with 360 degrees to reproject correctly. Your current image simply won't work.

Taking the images from the location of the scanner is not mandatory, but can be very helpful if the scanner position is stored in the point cloud's metadata. Then you only need to create Bookmarks from the scanner positions, move to each one, and create the Image Projection at that place to avoid guessing where it should be placed. Then you just need to adjust to rotation about Z.
Borislav "Bobo" Petrov
Product Specialist
Thinkbox Software Inc.

totte921
Posts: 3
Joined: Wed May 03, 2017 8:32 am

Re: Image projection

Postby totte921 » Thu May 04, 2017 3:39 am

Hi!

I tried to export an Equirectangular (LatLong 360 degree) image from PTgui and changed the horizontal Fov parameter in Sequoia Perspective mode to 177 degree (It seems to be the maximum) . But I could still not align the image in an easy way. The align tool did not help so i tried to adjust the picture manually but it is to much work to only get a small view in correct position. This is what I accomplished:

Image

I can upload my files if you wanna try, maybe that's something I'm doing wrong.

https://liuonline-my.sharepoint.com/personal/eriol726_student_liu_se/_layouts/15/guestaccess.aspx?guestaccesstoken=5XeVcY4fNqMliOIqaI14tEqgqH%2fJENpicLY3H5Q59xE%3d&folderid=2_1414c87671cec4d8fbbe544e89ed2a740&rev=1

jedfrechette
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Joined: Mon Apr 06, 2015 2:32 pm

Re: Image projection

Postby jedfrechette » Thu May 04, 2017 9:35 pm

For what it's worth I was never able to get equirectangular projection working either. See tests in this thread:

https://forums.thinkboxsoftware.com/vie ... 12&t=14784
Jed

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Bobo
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Re: Image projection

Postby Bobo » Fri May 05, 2017 12:56 am

totte921 wrote:Hi!

I tried to export an Equirectangular (LatLong 360 degree) image from PTgui and changed the horizontal Fov parameter in Sequoia Perspective mode to 177 degree (It seems to be the maximum) .


My bad, I intended to type "Sequoia Panoramic" and typed "Perspective" instead. Sorry! Panoramic supports 360 degrees, see if it changes anything.
Borislav "Bobo" Petrov
Product Specialist
Thinkbox Software Inc.

totte921
Posts: 3
Joined: Wed May 03, 2017 8:32 am

Re: Image projection

Postby totte921 » Tue May 09, 2017 9:31 am

I changed the projection to Panoramic 360 an used the alignment tool to project a region of my lat long map at a building and it projected it good without adjusting the ofsett to much. But everything far away from the alignment markes appeard very wrong. Now I'm trying to project over these regions with a new Lat Long map which leads to I project over ther region that was correct. It seems like one images alwas have to lie over an other but I want they to melt together. A tool for erase parts of an image projection would be nice.

I also noted that somtimes when I importing a Lat Long map the ratio between Horizontal and Vertical Fov becomes wrong. I always want Horizontal Fov to be 54,4 dergrees and Vertical Fov to 37,8 degrees because of my 35mm lense. But somtimes (not always!) Sequioa change this ratio automatically to something wrong and I cant reset it.


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