[ptx] Hugin architectural projection tutorial

[Stroller]

Hi there,

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. One would  
think that working on only one image would be easier than working on  
many, so I don't know how I'm going to get along when I start  
stitching panos with Hugin!  ;)

The original image (resized & converted to jpeg - I've been working  
with a 45meg tiff) is at http://photography.stroller.uk.eu.org/ 
Problems/Hugin/Original.jpg

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.

I initially tried setting control points for two vertical lines down  
the sides of the church tower and when this gave unsatisfactory  
results (see <http://photography.stroller.uk.eu.org/Problems/Hugin/ 
Hugged.jpg>) I then added control points for a third vertical down  
the right-hand side of the building, as in the screenshot at <http:// 
photography.stroller.uk.eu.org/Problems/Hugin/Screenshot.png>; the  
results of this were even worse!! <http:// 
photography.stroller.uk.eu.org/Problems/Hugin/Hugged2.jpg>

The tutorial does not mention any need to use control points for a  
horizontal line, but for my last attempt I tried this along the line  
of the roof. Once the resulting image has been rotated is somewhat  
better, but I'm still not entirely happy with it, and I'm inclined to  
think that I've been doing something wrong throughout the earlier  
images. The top of the image is more curved than I expected, but I  
supposed this is normal, and that I _should_ have expected it; the  
door shows distortion from the manipulation, yet the tower itself  
really does not seem to have had the perspective improved so much.  
<http://photography.stroller.uk.eu.org/Problems/Hugin/Hugged3.jpg>

At each stage I have clicked the "Optimise Now!" button, but have  
left everything at their default settings, as I had no idea what to  
adjust. Optimisation is therefor of "Positions (incremental, starting  
from anchor)" and "yaw" is not ticked (as in the tutorial).

I would be very grateful for any advice on how to improve these  
results and apologise to the list for my poor understanding,

Stroller.