Using PTools

How can I know how to set the parameters in the Create Panorama dialogue?

For this reason PTools can find the missing parameters and uses a concept that many other stitching programs use: corresponding features (or controlpoints). From the overlapping area of two images the user places corresponding controlpoints on the locations of distinctive features in both images showing the same 'object'. PTools requires to be given the coordinates of these locations in its own variety of script.

E.g. a line c n0 N1 x374 y554 X58 Y560 in a Ptools stitcher script means that a control point with coordinates (374,554) in image number 0 has coordinates (58,560) in image number 1. Given this information PTools can derive pitch/roll/yaw and even the degree of barrel/pincussion distortion in the lens. You just need to ask PTools using a v-line - this is a script line where you tell PTools what unknown variables - yaw, fov etc you want it to solve for.

You give the program the control point information in c-lines There are currently three ways to generate a c-line:

1. Open the Info window in Phototshop (or whatever) and write down the displayed coordinates by hand.
2. Use the PTools Pixel Picker
3. Use PTools 'Read Control Points' command which is described now.

This is how to get PTools to scan your images for contol points: Create a text file with a text editor but leave it blank. Save it in your working directory as control.txt. Open the first image which has been marked with the control point markers (it has to be an single layer image - flattened), then select Filter - Panorama Tools - Adjust. In the Create Panorama dialogue select Read Control Points and Use Script. Press Browse and select the file control.txt in your working directory. Back in Create Panorama Press Ok. Within a second PTools has scanned the image for control point locations and added the following lines to your control.txt:

c n0 N-1 x374 y554 X0 Y0
c n0 N-1 x363 y483 X0 Y0
c n0 N-1 x363 y334 X0 Y0
c n0 N-1 x372 y230 X0 Y0
c n0 N-1 x369 y113 X0 Y0

c n0 N1 x374 y554 X58 Y560
c n0 N1 x363 y483 X44 Y488
c n0 N1 x363 y334 X43 Y335
c n0 N1 x372 y230 X54 Y230
c n0 N1 x369 y113 X54 Y109

p w600 h300 v60
i w480 h640 f0 v42 r0 p0 y0
i w480 h640 f0 v42 r0 p0 y30

Because you want to know about the roll/pitch/yaw that happened to your camera before taking the second image (which is image number 1 for PTools) you add the line

v r1 y1 p1

# (*) - optimized         (p) - preset
# Image No 0:
# Yaw:	0 deg (p)	Pitch:	0 deg (p)
# Roll:	0 deg (p)	HFov:	42 deg (p)
o f0 r0 p0 y0 v42 -buf

# Image No 1:
# Yaw:	28.0078 deg (*)	Pitch:	0.114398 deg (*)
# Roll:	0.841227 deg (*)	HFov:	42 deg (p)
o f0 r0.841227 p0.114398 y28.0078 v42 +buf

Using scripts

p v360 f2 w600
o f0 r0.873   p0.174    y0.735    v90        -buf
o f0 r0.564   p0.623    y90.992   v90  +buf  -buf
o f0 r0.651   p0.524    y180.194  v90  +buf  -buf
o f0 r0.663   p0.552    y270.362  v90  +buf  -buf
o f0 r-89.02  p90.91    y0.112    v90  +buf  -buf
o f0 r90.154  p-90.38   y0.834    v90  +buf

• Open your first file and select Filter - Panorama Tools - Adjust. In dialog Create Panorama select Insert and Use Script. Click on Browse and select script.txt in your working directory. Back in dialog Create Panorama click Ok. The first file is now distorted and inserted into the buffer. Open your second file and again select Filter - Panorama Tools - Adjust. Since PTools has remembered the previous setting just click Ok. Repeat this until all your images are processed. Then select Filter - Pan Controls - Get Pano. The resulting pano is now opened.
• The easyer way is to install the PTStitcher. This handy piece of software can create panoramic images without the use of any image editing program. You just put the file script.txt in PTStitcher's directory and then simply drop all input images onto the application icon of PTStitcher. The default output is a PICT file (BMP on windows). With little changes at the p-line of your script other fileformats such as VRML, Live Pictures ZoomIt and even QTVR movies (latter only with the macintosh version) can be created by PTStitcher.

To sumarize...

1. Write a script containing one p-line - what kind and size of target panorama do you want.
2. Insert as many i-lines (information about the images) to the script as you have source images are to be processed.
3. Place control point markers and image numbers in your source images.
4. Let PTools scan these control point markers and generate c-lines (which tell the program the locations of the corresponding control point markers).
5. Add a v-line (to tell the program what parameters you need to find) and let the Optimizer generate o-lines for you (which tell the program how to build the panorama with the values it has Optimized for each image).
6. Open each source image in and let PTools run your script - or use the PTStitcher instead with no scripting.
7. Finaly it is agood idea to sharpen your final panoramic image.

What is 'stitching by hand'?

1. If you did not select the correct HFOV, the edges of the component images will probably not fit.
2. If you did not correct the barrel/pincushion distortion since you do not know the radial factors the edges will probably not fit.
3. If you did not use a tripod, the edges will probably not fit once more. Try to rotate or transform the layer in this case.
4. If your camera has no exposure lock, a seam will be more or less visible (see my example). The Adjust command provides color correction in this case. You might try to correct the color balance with your image editing program, which is fairly difficult with more than two layers. Another possibility to solve this problem is to switch to quick mask mode and use the gradient tool to select an area as shown here (lower layer is invisible). Then switch to standard mode and press delete. If you make the lower layer visible again you will see that the upper layer is faded out, which gives a soft seam.
5. If you want a 360 degree pano it should wrap around correctly. Then you must cut one of your images in two pieces and use them as border images (left and right border). You can test if the right and left edges fit together when the flattened image is wrapped around: In Photoshop use the Offset filter with the option wrap around selected. Select a horizontal offset of e.g. 100 pixels. If you can see an misalignment like in the image below, your image is sheared. Try to find out how many pixels the vertical offset is (e.g. by selecting one strip and move it vertical with the cursor buttons - count how many times you depressed them). After you found out, close your unsaved image and reopen it. Then select Filter - Panorama Tools - Correct. Use the Shear option and set a vertical shift of twice the number of pixels you counted before. If you have done everything right, you can apply the offset filter again, but no seam will appear this time. Try to find out how many pixels the vertical offset is (e.g. by selecting one strip and move it vertical with the cursor buttons - count how many times you depressed them). After you found out, close your unsaved image and reopen it. Then select Filter - Panorama Tools - Correct. Use the Shear option and set a vertical shift of twice the number of pixels you counted before. If you have done everything right, you can apply the offset filter again, but no seam will appear this time.

How do I produce a QuickTimeVR file?

#VRML V2.0 utf8

Viewpoint {
   fieldOfView    .5
   orientation    0 1 0 0
}

Vista
{
   type "SPHERE"
   filename "my_pano.jpg"
   vFov -1.6 1.6
   pitchRange -1.6 1.6
}