Tuesday, June 1, 2010

Lens calibration in PTGui

I have found that pole/monopod/handheld panorama projects are much more successful when I insert lens calibration parameters created from a previous "very good" stitch in the Lens Settings tab.

This link from ptgui.com tutorials explains how to create a lens calibration for a particular lens/camera combination.

This is a screenshot for an AF Fisheye Nikkor 16mm f/2.8 on a D700 camera. These were saved after building a particularly successful architectural panorama (1 Bank of America Center Urban Garden).
Retrieving these settings from the Lens Database in the Lens Settings tab when starting a project often yields a panorama that needs very little mask editing to correct stitching/blending errors in the .psd output file. That's a huge time-saver.

The urban garden example was shot on a tripod with a panorama head, so the geometry of the images was accurate. When we shoot using a monopod, or when handholding, the images generally are not accurately overlapped, or always shot on the No Parallax Point. Using a lens calibration allows PTGui to more easily find overlapping control points - it gets the images "in the ballpark" first.

Follow the instructions in the tutorial, and begin generating lens correction parameters for the lenses you most commonly use when shooting panoramas.

There are more images from the 1 Bank of America Center shoot on our panorama page at charlotteobserver.com. The 30th floor terrace and interior as well as the workers atop the atrium were made with a circular fisheye lens on an FX format camera, shooting four images around at roughly 90 degrees of overlap. Using the lens calibration for this camera and lens combo cut quite a bit of time from production.

No comments: