[Fwd: Re: [ptx] using hugin to stitch large scans]

[HaJo Schatz]

One day (in the near future) I will patch my MUA to reply to the "List-
ID:" header rather than the "Reply-To:" header...
 
-------- Forwarded Message --------
From: HaJo Schatz <hajo at hajo.net>
To: Marek Januszewski <spec at webtech.pl>
Subject: Re: [ptx] using hugin to stitch large scans
Date: Tue, 22 Feb 2005 00:15:57 +0800
On Mon, 2005-02-21 at 10:34 -0500, Marek Januszewski wrote:
> Hello,
> 
>   I have a large map I would like to stitch from 4 A4 scans with minimum 
> of work. Autopano will find the same points without a problem, but 
> what's next? should I setup some very large FOV? Did anyone do this before?
I'm doing exactly this quite successfully with hugin -- even though
hugin is today not really "tailored" for it, you'll have to intervene
manually to get it done. 

The idea is essentially to optimize the shift parameters only. I have
collected my own "readme" for this task a while ago. Let me just post it
for you. Any questions, let me know...


Greetings,
HaJo

---------

October 6, 2004, HJS, V 0.1

These are the HK Country Side Series maps, all scanned with some
overlap. File naming is as follows:

front-a-1.jpg
  I   I I  
  I   I +- horizontal sequence from left to right
  I   I 
  I   +--- vertical sequence from top to bottom
  I
  +------- front/back for page 1/2 of the map

If individual blocks are to be used, note that they usually have to be
rotated first as these are raw blocks as scanned. Save them with the
correct adjustment (and name xxxx-adjusted.jpeg) for later re-use!

It's not practical to stitch all parts together to recosntruct the
whole original paper map -- in a decent resolution, this would lead to
an extremely large file size not processable with an avg
computer. Note, however, Panotools can stitch the map OK, the only
problem is picture viewers & editors processing it later. Ie you may
stitch a low-resolution map ok.


Hence, stitch individual blocks as you need them. All segments are
scanned with overlap and can be stitched with PanoTools/Hugin as
follows:

* Load Pics:
- Load all the required blocks into Hugin

* Lens parameters:
- Set the lens of each pic to Equirectangular
- Make sure d/e/g/t are _not_ inherited
- Set the focal length to about 50

* Control points:
- As first step, define control points for Image pair 0/1 _only_

* Project:
- Set the stitch project to Equirectangular

* Optimizer:
- Set "Optimize Custom parameteres below"
- Disable all parameters
- Choose "Edit script before optimizing"
- In the script, look for the v-line, add a "v d1 e1" to optimize only
  d and e of pic 1
- In a next step, choose r1, optimize and again enter "v d1 e1"
- Note: Preview shows a distorted image, final stitch should be ok
though

- Repeat above steps with Image pair 1/2, ...
- Finally, optimize a/b/c/d/e/g/t. Do _never_ optimize y/p !!

! Hugin has a bug handling more than 9 pics (in the lenses tab). If
you have >9 pics, save the project, fix the file in a text editor and
re-load it in Hugin, then it's OK.

! If lat/long lines are not straight, introduce intra-block
horizontal/vertical lines as required and re-optimize. It may help to
adjust r0 correlty first. Accurate r0 can be measured eg with the
Gimp's roate function which shows a grid.

! If loading a project which has control points set for several blocks
already, d/e of all blocks has to be optimized in one step.

! It helps to have some scratch open in eg Emacs to be copied into the
optimizer script, eg something like:

v d1 e1
v d2 e2
v d3 e3
v d4 e4
v d5 e5

And for a final optimizer run:

v a1 b1 c1 d1 e1 g1 t1
v a2 b2 c2 d2 e2 g2 t2
v a3 b3 c3 d3 e3 g3 t3
v a4 b4 c4 d4 e4 g4 t4
v a5 b5 c5 d5 e5 g5 t5


> 
> --
> best regards,
> Marek
-- 
HaJo Schatz <hajo at hajo.net>
http://www.HaJo.Net

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