View Full Version : two questions (1 camera, 1 stitching problem)
04-20-2009, 05:22 AM
Hi there, I have just gone through the proces of establishing the corrrect rail positions for my Eos 20d with efs 10-22 lens. I am slightly worried that my upper rail settings(which look perfect to me) are different to the settings that I have seen for this combo elsewhere on the forum. I am happy that the lower rail is central at 54mm. The upper rail however is as far back as it can go on the rail, and this is with the camera plate with the NN¬£'s mounting thread on the lens side of the cameras tripod thread point.
I have seen setting mentioned of 97mm for this lenses and camera, but at these setting I can see a lot of parallax movement. My setting is nearer 107mm to acheive no parallax (with the plate as far back as it will go). Have I got this wrong?
My first panos have come out OK bar one constant thing that I am struggling to understand whats happening.
exif info is showing as full frame, 10mm (which alters to 12.38 on alignement), should I be changing this to recilinear normal?
On and interior shot of a room in my own home I tried 2 different methods. (1) 6 @ +30, 6 @ -30 plus Zenith and (2) 4@-60, 4@+60 and 8@ level horizon.
The second setting has worked a lot better than the first, but both have shown stitching errors on the exposed wooden overhead ceiling beams. The beams are actually kinked in paces and there is a blurry missmatch at these points.
After alignment, I have gone into the control table and deleted anything over 4 points out and there seems enough points for the stich OK. Any ideas what am I doing wrong?.
If these is a way of posting a sample, can you let me know what size setting will make the file size small enough to post but still be good enough to see the problem?
04-20-2009, 06:19 AM
The lens should, of course, be specified as rectilinear. See Tools->Options->Exif for the rule that PTGui applies and adjust so that it assumes the right type.
Don't delete control points simply because they are over 4. Delete them or correct them only if they are inaccurately positioned. make sure you have a good spread of control points - not bunched in the middle of the overlaps. Select Advanced mode and in the Optimizer tab, choose "Heavy + lens shift" in the Minimize lens distortion pull down list. Running the optimizer should then give an improved result. Your 2nd method of shooting is to be preferred.
04-20-2009, 06:58 AM
Thankyou John, that was very handy. I altered the EXIF setting to rectilinear normal and used the maximise setting you stated and the beams have stitched well this time. Thanks.
Just out of interest, I notice that when I output a 360 the default quality setting is 70%. I need to do a couple of interior 360s for a website on Wed. Can you give me an idea of some basic dimension settings for ending up with a file that is a good size for websites. Not sure if should be reducing the quality or reduce the pixel dimensions to achieve this?
I only have the pTgui standard and not the pro, if that makes any difference to the final options.
04-20-2009, 09:50 AM
There's no simple answer - it depends on how you are displaying the panorama and at what size, and what file size you are prepared to tolerate in the interests of an acceptable download time. It's usually a compromise. For a fullscreen 360x180 QTVR pano, you need an equirectangular image of between 5000x2500 and 6000x3000 pixels. When this is converted to a .mov file, it is the cubic tile size and the quality setting that determines the overall quality of the result. Generally, the tile size can be set to pano width divided by pi (3.142). The quality setting needs to be set to the lowest value that avoids the worst compression artifacts such as banding and blocking in blue skies or blank walls. 70% is typical, but lower values will result in a smaller .mov file. Some subjects compress well (i.e. produce a small .mov file), while others having a lot of detail compress less well and produce a bigger .mov. So you can try different tile sizes and quality settings to get a final result that is acceptable. A good quality fullscreen pano would typically end up at 2 to 3 MB. If you only require a smaller window, then you can scale things down accordingly, specifying a smaller tile size. (The window size parameters have no effect on the file size). A few trials will quickly tell you what's needed. If you stitch to an equirectangular image (preferably TIFF), you can use Tools->Convert to QTVR to convert the panorama to .mov, or you can use the free version of Pano2QTVR. Other programs are available to generate Flash panoramas if required.
04-20-2009, 11:39 AM
Thanks, that gives me a good starting point to work from.
You mention the pano2vr software. I have looked at this and can see that it scan be used for flash formats etc. When using QT.mov as a viewing format, doesn't the PTGui handle the whole thing?. Are you suggesting taking the pics as Tiffs or a Tiff from a Raw shot and working within PT with all Tiff's up to the point of exporting to the finished 360 x 180 .mov?
04-20-2009, 01:59 PM
If you only want to generate a QTVR format, then PTGui can handle that. However, you might well want to do some post-processing of the stitched output to correct stitching errors or to patch the zenith or nadir before converting to .mov. It's advisable to use TIFF files throughout (including converting from RAW to TIFF rather than JPEG) to avoid multiple applications of JPEG compression, which can result in avoidable loss of quality.
04-20-2009, 02:11 PM
If some post tidying up is required, can I bring the processed file back in to PT for output to QTVR.mov? or is it best to use Pano2VR.
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