[ptx] Hugin architectural projection tutorial

[Martin Proetzsch]

Hi Stroller,

Am Sonntag, 12. März 2006 06:27 schrieb Stroller:
> I'm trying to follow the tutorial at http://hugin.sourceforge.net/
> tutorials/architectural/en.shtml to remove perspective / wide-angle
> lens effects on a building and I'm not having much luck.

I think there are two things you might have confused:

1. The bending of the image is caused by the projection you chose.The tutorial 
says" "Change the Panorama type to rectilinear and calculate visible field of 
view (we don't have enough photos for a full 360 degree equirectangular 
panorama)." This is done in the "stitcher" tab. The output image then has a 
more "normal" look.

2. The control points for your vertical lines are not set properly as can be 
seen in the screenshot at 
http://photography.stroller.uk.eu.org/Problems/Hugin/Screenshot.png
First deactivate "auto estimate". For a vertical line choose a point in the 
left image and afterwards a _different_ point on the same vertical feature in 
the right image (the bigger the distance to the first point the better). In 
your screenshot all pairs of points are nearly in the same place, probably 
due to hugin auto estimating matching points. The "auto estimate" feature is 
only useful for stitching images.

> I loaded this single image into Hugin & in the "Camera & Lens" tab I
> left "Lens Type" at the default of "Normal (rectilinear)". In Design
> parameters I set the focal length to 17mm, as I was using my Canon EF-
> S 17-85mm lens at its widest angle. This set "degrees of view (v)" to
> be 93 but I subsequently noticed the "crop factor" box and (in one of
> my later attempts) I set this to 1.6 (this suits my APS-C format
> digital SLR, I think?) giving a "degrees of view (v)" of 67.

This sounds correct. However, if you use the jpg-files this information is 
automatically extracted from the exif-header.

Regards,
	Martin