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Author Topic: Should we use Lens Profile Correction in Photoshop before importing into PScan?  (Read 4244 times)

rexsham

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I know PScan can undistort photos automatically using the detected feature points during the Align Photos step.
But what I am confuse is that if our camera has a built in lens profile in Adobe Lightroom, like Sony DSC-RX1, when we export the photos after exposure adjustments, should we also apply the lens correction profile to undistort the photos before importing the JPGs into PScan?
Will this affect the accuracy of the output of DEM and DOM? Better or Worse?

bigben

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No. Lens correction profiles don't include centre offset.

jrp

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I have a similar question: I have a sony a77ii and a sony 16-50 f2.8ssm (24-75ish equivalent). it's a wonderful lens, but rather high distortion. I have had results come out looking distorted as a result.

Is it preferable to use adobe corrections to go part of the way, then let PS finish the job, or is it best to give the fresh files to PS to work on all the way through?

Is there a procedure that can allow me to generate a lens profile in PS that I can reuse in future?

bigben

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No. Lens correction profiles don't include centre offset.

Distortion correction calculates a new distance of a point from the optical centre of the image.  If you have one process that performs this fron the centre of the image file and then a second process performs this from a different position, then the first process has screwed things up for the second one.

The calculation of lens parameters by Photoscan (and all of the image stitching applications I've used) is an optimisation routine, ie. The end result depends on the data you supply it.  Distorted models are caused by the lens parameters optimising to values that are not accurate for the lens. This in turn can be caused by a whole range of factors including inadequate number of images... At different angles... Poor image quality, too low GSD for the expected resolution etc...

You can either use Agisoft lens to calibrate your lens parameters beforehand, or save the lens parameters form a project that has worked well and then load these into subsequent projects.

rexsham

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Thank you very much bigben!