Processing HDR Imagery - workflow

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Terrence_SA
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Processing HDR Imagery - workflow

Post by Terrence_SA »

Hi All

Has anybody developed a decent semi-automated workflow for externally processing HDR Imagery Captured by the VZ400 and bringing it back into RiScan Pro?

I have a project of 90 scans where we have done HDR imagery. The RGB quality is important as the client will be using the data for Asset Management.

Ideally I'm looking for some good open source software that I can write a routine for to automatically search, process and replace images in the Raw Data Folder.
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Re: Processing HDR Imagery - workflow

Post by jedfrechette »

What kind of processing do you need to do?
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Re: Processing HDR Imagery - workflow

Post by joe.3dlm »

I'm interested in this too - looking forward to seeing what people come up with

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Re: Processing HDR Imagery - workflow

Post by Andy H »

Will put thinking cap on


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Re: Processing HDR Imagery - workflow

Post by dhirota »

Are you using the standard Riegl 7 sequence photo collection (20mm lens/f2.8), using the camera menu to generate multiple images (3,5,7,11 separate images) using a Nikon? or Canon with a different lens? Or a Nikon D800E/D810 with the camera firmware menu HDR set to on?

Are you looking to generate 96 bit *.EXR HDR to be tone-mapped later?
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Re: Processing HDR Imagery - workflow

Post by christopherbyrne18 »

Hi Terrence,

I used to work for the Riegl distributor here in Perth. This came up at distributor training I attended a few years back. The answer,back then anyway to bring the data into and external stitching package. PTGUI is probably your best bet as it can stitch and blend HDR imagery. The Riegl guys mentioned making sure not to rotate any of the images. By default if I remember correctly they are captured sideways due to the camera mounting.

So the process would be something like create a equirectangular image by stitching all the sets of bracketed images together and blend the images. There are a few options regarding the settings for the HDR blending:
HDR.jpg
There is also a batch stitching which I'm sure could be set up to automate the stitching for you:
HDR.jpg
You would need to output cube images from each of the equirectangular images and import these back into RiSCAN Pro making sure they are in the same format they were before export.

One thing to watch out for...

There could be issues with the stitching depending on how much overlap you had selected for the camera settings on the scanner. Image stitching software rely's on common control points to stitch the images. This means you need good overlap between adjoining images whereas the camera on the VZ400 is calibrated with respect to the scanner CSYS and uses this for mapping to the point cloud data data in RiSCAN. By default there is little overlap between the imagery. I would turn the overlap (amount of images captured) up on the camera kit if I was planning on exporting the data for stitching.

I have never personally performed this so I would recommend contacting Riegl directly. They might have documented a workflow by now, it was fairly new back then. It would take a little figuring out to begin with but definitely do-able....

Cheers,

Chris
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Re: Processing HDR Imagery - workflow

Post by Terrence_SA »

Hi Jed, dhirota - I am trying to blend the 4 images captured into a single equirectangular image to bring back into RiScan Pro. Yes I am using the 7 image/scan setup with a NIKON D300. The camera was set to take 5 images per position (ie. 35 per setup)

Christopher thanks for the detailed response. I have previously used HugIN for stitching and equalisation of Panoramic imagery - it creates smoother images then the current RiScan Pro function. I did initially have a few problems with overlap but have sorted this out by ensuring we have at least 20%.

I have experimented with a few HDR processing suites but have always had an issue with bringing the imagery back into RiScan. I'm guessing the rotation may have been the problem. But I am also wondering if the naming of the image file needs to be identical to the captured name - "Scan Name_Image001"?

I will experiment with the batch processing and see how much it can be automated.
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Re: Processing HDR Imagery - workflow

Post by dhirota »

I have tried what you are attempting to do now, several years ago. We have a VZ400 with a Nikon D810 and 20mm lens. Part of the problem occurs if you are in an outside environment like Hawaii where the clouds are moving which generates changing lighting conditions. If you are inside, where the lighting is constant it is less of a problem, but the download of the images to the VZ400 takes time unless you are loading them directly to the SD card.

Speaking with others that have tried the same approach, it seems that one approach would be to take the 5 images, generate a HDR tone-mapped image, and place it into the proper location within Riscan Pro with the proper name convention after deleting any multiple images. Use a batch process for the group and then let Riegl Riscan Pro finish to completion to the colored point clouds. If you are looking for only for the tone-mapped equirectangular image to bring back into Riscan Pro, that may be problematic at the present time, but will probably corrected in the future.

I will be attending Intergeo 2015 and speaking to several people who have the same interest.
Dennis Hirota, PhD, PE, LPLS
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Re: Processing HDR Imagery - workflow

Post by christopherbyrne18 »

Hi Terrence,

The issue with getting them back into RiSCAN Pro will be the rotation of the images, make sure they are not changed from the original exported images. Make sure the image naming is the same and you will most likely need to select the images and re-apply the camera calibration to the re-imported images. If you don't take care of this the images won't map properly. This may not be exact, its been almost 2 years since I used RiSCAN in anger.

Cheers,

Chris
Terrence_SA
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Re: Processing HDR Imagery - workflow

Post by Terrence_SA »

Thanks for the replies I will let you know how I get on.
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