HPU Modern Media Systems Fall 2009

Author: Black Sand (blacksandhawaii)
Tags: fofs, hawaii, pacific, university, hpu, oahu, faculty, students, modern, media, systems, beretania, street, fort, mall, 1188, catholic, church, portuguese, memorial, statue, multimedia, program, department, of, communication, college, humanities, and, social, sciences, peter, britos, filmmaking
Date taken: October 15, 2009
Date added: October 16, 2009
Bookmarked: 0 times
Total views: 726 views

This conversation page has been viewed 0 times.

All Snapshots (22 total)

Lens distortion

If a 50mm lens was used, stitching the frames would have been almost flawless due to the almost zero lens distortion. Using a point and shoot camera set at long zoom does not provide the ideal DOF. I would suggest not using auto mode but to use the Aperture Priority (Av) setting and at f11 or higher to avoid out of focus subjects.

Comments:

1. Lens distortion is NOT the issue here. This looks like accidently moving the tripod, with the added problem of the stitcher not being able to match the already mis-aligned frames. Auto exposure should not be used - there will be too much difference between frames with varying contrast across the image. Most P&S cameras apertures go to f/8, rarely f/11. Yes, use the smallest aperture opening (largest aperture number), and auto focus for images with large variation in subject/lens distance, but use manual exposure. Manual exposure gives a more accurate rendering of the overall lighting a a particual scene, and avoids the inevitable extreme exposure differences as the camera moves from bright areas (sky) to "normal" exposure areas (buildings and land, as examples).
http://gigapan.org/gigapans/22431/ shows how using manual exposure and auto focus preserves the integrity of the overall lighting situation present in the composition, and also allows most of the image to remain in focus (well, then there's the case of moving subjects).
http://gigapan.org/gigapans/31404/ is an example of what occurs when using any auto exposure function.

Posted 4 weeks ago by Richard Palmer (Apapane)

2. appreciate the analysis. rick, do you know the biggest unit my gigapan will hold? i'm looking to see if we can get more lens length than what i have for the magazine shoot.

Posted 3 weeks, 6 days ago by Hawaii Pacific News (hawaiipacificnews)

3. Hi Rick, sorry to say but the whole photo is distorted. The stitcher does a good job and yes, I agree that movement further generated that particular section which I should have also mentioned. However, you must agree with me that anything which starts to stray too far away from 50 mm you WILL begin to experience distortion (misalignment, parallax error), which will require an additional stage(s) of correction. You can 'cheat' to some extend using software but not entirely. Since P&S have limitations, I just think that they shouldn't be used for these projects. You can't set to manual focus and shoot infinity, etc. I just can't help but think of the opportunities and time wasted, not to mention storing a lot of could-have-been better giga-size files. Please don't take this negatively. I'm all for the project, I just wish the process could have been a little better.
Just some additional readings for those who are interested:
http://vision.ucla.edu/~hljin/papers/cvpr08.pdf
http://www2.iath.virginia.edu/panorama/print/version2_pdf/PanoGuide.pdf

Posted 3 weeks, 6 days ago by Mike Ang (mafotografix)

Add a comment