Here we make comparisons between mathematical purity, the analog real world, and how the QTVR tools help to merge the two help to simplify QTVR content creation. Common questions are answered and conventional wisdom is challenged. A broad range of information is presented ranging from the differences between inside and outside panorama creation, to dealing with dark banding and vignetting inside your panorama, to choosing the right camera for the right situation.
Basic QuickTime VR quality standards
Take enough images to get good overlap for the stitcher to work with. The stitcher works with as little as 15% to 20% overlap. The larger the overlap the better the stitcher's algorithm is at matching the images. The bigger problem has to do with eliminating the dark vertical areas around the stitch points. The problem of dark areas at the stitch points is caused by stitching together the edges where the image is darker at the edge than it is at the center of the frame. This is caused by a combination of low quality lenses which have exposure roll off at the edges as well as different exposures of the individual images. To correct for this, a larger percentage overlap of the images in the panorama is required. For example, a high quality lens may need only a 20% overlap to get a good panorama if the exposure of the images are fairly constant. If there are definitive exposure differences (light and dark parts) within the panorama, you may require 50% or more overlap with the same lens to get the images averaged out to a consistent, gradually changing, level. An overall good starting point for image overlap is in the 30% to 50% range. These banding problems can be addressed in Photoshop, but you are better off taking more images as the Photoshop solution is very tricky and the results are not that much better than leaving the images alone. A set of image overlap examples can be found on the Tips and Techniques page.
|
|
Example of 10% image overlap |
|
|
Example of 55% image overlap |
Once you have a decent panorama, there are a few Photoshop touch ups that may be required. The first is to clean up the smudged sections of your panorama at the top and/or bottom of your stitched image. These are created by using the "fill" argument in the stitcher tool and are the result of a not quite level camera pan head, or panning plane. Not doing a "fill" will result in an empty area, so you are better off using this command. The other things to look out for are crescent shaped wedges also located along the top and/or bottom of your panorama. What you are seeing here is the edge of the lens vignetted against the image. To solve these little anomalies, you can either get a better lens, have more overlap, and/or fix them up in Photoshop like you do with the smudged sections. Photoshop is your friend, and the Photoshop rubber stamp tool is your best friend.
|
|
|
 |
 |
Once you have the panorama all fixed up, you are ready to make a QuickTime VR movie out of the thing. The lesson here is to create a panorama window of the appropriate size. Just because it runs great on your system does not mean that it will run great on a slow Windows box. In addition, think about setting the zoom range to prevent the user from splattering into the panorama when they zoom in...unless you want this effect. You will also want to be sure you have a reasonable aspect ratio for the panorama - too wide and things look unnatural, too narrow, and things feel to restricted. Think about the effect you want and set the window size and zoom range accordingly.
Standard motion picture screen aspect ratios:
- 1.66:1 (flat standard screen)
- 2.35:1 (cinemascope wide screen)
Quality is not a purchased privilege
There are those who believe that the once a week photographer can not compete with the skills of a professional in the realm of QTVR. The argument goes something like this: "The day to day learning process of the professional becomes years and years and does not come for free." So far the argument is a sound one; experience will make you a better photographer. The argument then drops into the theory that "some professionals have invested tens of thousands of dollars on equipment in addition to countless hours invested in learning. Some have offices and studios, while others have staff and families to support." What this has to do with quality we do not understand. It sounds like a lame attempt at sounding superior while applying a little guilt based on the idea that if you spend thousands of dollars and countless hours of learning then you deserve to be better than the rest. This is the same type of argument that was heard ten years ago when the desktop publishing craze hit the world. Many typesetters scoffed at the idea, and now very few are still in business. QuickTime VR content is very easy to create, so easy in fact that just about anybody can do it. So here comes the rub: It is easy, anybody can do it. We need to make sure we keep a high standard of quality in our work less we come witness to the same destruction of quality seen in the desktop publishing world. Learn to advance the trade.
Panoramas: fast or forgotten
Large and extravagant productions for creating QTVR content are great for long life, high profile titles such as "The Lost World" or "Tour of Major European Cities" which may take several years to create. For the relatively short lived promotional panorama or event based panorama, QTVR content creators need to make use of low cost, quick turnout techniques to produce their content. In addition to doing all of the software work, this also involves using a good quality digital camera and taking all the photos yourself to keep expenses down. This has become the norm in other fields like desktop publishing and photo journalism, and there is no exception with QTVR. Using this technique, we were able to create a 39 node panorama of an ocean side camping facility on the California north coast. Photo time was a few hours, software time was 15 hours to create the multinode panorama.
Lenses and nodal points
There has been some question about the appropriateness of zoom lenses for QTVR work. One expert stated "The nodal point of a zoom lens varies when you change from one lens setting to another. This would adversely affect QTVR development. Hence zoom lenses should not be used for QTVR work." While it is true that if you CHANGE the setting of the zoom, you will affect the resulting panorama. The effect of changing the zoom BETWEEN PANORAMAS will result in panoramas that are physically smaller or larger than the others (different stitched image dimensions). While this is not a problem for single node movies, this is a problem for multinode movies developed to run under QTVR 1.0 environments. The QTVR 1.0 tools and players (including the Netscape plugins) can not handle panoramas of differing image dimensions within a single multinode movie. The nodal point of the lens will change a bit as you zoom in and out, but really only matters when there are objects close to the camera; correct nodal setting will prevent parallax between near and far images. The bottom line: Any lens will work for a panorama so long as the same lens setting used for a complete panorama or set of panoramas used in a QTVR 1.0 multinode movie. Don't be too concerned about the rectilinearity of the lens either, just watch out for using fish eye lenses as the stitcher really does not like them. As for lens nodal point: for distant objects, all you need to do is get the lens somewhere above the rotation point. Exactness is for the theoretical mathematician, the QTVR tools are good about fudging the input to make it look right for output. Another thing - QTVR is a creative medium - there is no "should not be used for QTVR work". This is an anything goes creative outlet. If the resulting images are interesting, then you have a good creation.
Camera orientation
A question was recently posed as to the validity of panorama images taken in landscape orientation rather than portrait. An interesting question, resulting in this odd answer: "I would suggest that the photographer reshoot in "vertical". Putting it together horizontally will really cause problems in all around quality." Interesting answer, but not a lot of vision. There is no right or wrong way to orient you images for a shoot - either way works - vertical or horizontal. As long as you and/or your client are pleased with the results, do it. The claim that shooting horizontal will cause quality problems is incorrect. The only difference in a panorama shot landscape is lower vertical resolution than you would get if you shot portrait. This is photography folks, it is an art form. There is no right or wrong way.
Image quality
If we all had our wish, we would have photo developers and PhotoCD burners in our houses and it would be free. Since this is not the case, there is an alternative for most QTVR work. Use a good digital camera (priced in the under $1000 USD range) and a PC-card (PCMCIA) for image storage. These cameras have decent dynamic range and image resolution. If one of the image channels is a bit noisy (usually the blue channel), it is a simple matter of cleaning it up a bit in Photoshop. Most of the cameras in this price range produce excellent images when their high quality JPEG compression is used. The PC-cards are sturdy and moderately priced at $400 USD for either a 20MB RAM Type-II or 260MB HD Type-III. These cameras weigh in at under a pound and generally have the ability to attach a 28mm equivalent lens for outdoor QTVR work. For web or CD images, this is not a bad choice. You can clearly get better results by using PhotoCD, but at what cost? You have to deal with and listen to the rules of diminishing returns.
Cameras for QTVR work
First off, any camera will work for shooting QTVR panoramas. As we have stated above, any lens will work. It follows, therefore, that any camera will work since a camera is simply a container to hold a lens next to the film for exposure. Now that that's out of the way, we need to choose the camera for our work. For places where the camera is in danger of being dropped, getting wet and muddy, etc., you should stick with a trusty traditional camera. By trusty, one that is capable of being banged up, dropped, can handle some moisture, and run without batteries in full manual mode. As a wise man said "...for the rough stuff I use my 25 year-old 'hockey puck' Nikon F. Fully manual. No batteries. No lightmeter (I use a hand held Gossen Lunasix/F anyway). Doubles as a heavy object to throw at trees when bored...". For underwater work you can not beat the Nikonos V with a 20mm lens. You can also use those cheap underwater throwaway cameras and get good results. For average above water photography, you can use whatever camera you like best - the question you have to ask is "digital or film?".
Digital Cameras
It is possible to use digital cameras for VR panoramas and the results are not much different than the standard resolution used when making VR panoramas from photo CD....provided you have a good digital camera. We have used a cheesy Canon video still camera (RC-250) which records still video images onto 2" floppy disks - 50 images per disk (with this we can get 3 panoramas per disk). The resolution is not great at 320x240, but it works. We can spend a few hours and record 40 nodes, bring these images into a PowerMac 8500 with the video-in port, stitch, create a walkabout/panabout, etc. in about 15 hours of work. These panoramas and walkabouts are perfect for the web - files are small and download fast. So, for a small amount of cash, you can do some exciting work.
For panoramas of good quality, you need a digital camera with a resolution of at least 700x500 and a wide angle lens (a 28mm equivalent would do nicely). The other important requirement is on-camera storage space. If you can find a camera with PC-card (PCMCIA) Type III ATA support you can snap in a 170MB PC-card hard drive and record your images. High quality JPEG compressed images in the 700x500 range take about 256K per image. At 170MB, that is 680 images. At 16 images per node, that gives roughly 40 nodes before you need to download to a computer or snap in another 170MB PC card. The important thing about on-camera storage is the ability to shoot multiple nodes w/o getting a computer involved - you can get in and out quickly and do all your work in post. There are some digital cameras that have LCD viewfinders. We would pose however, that these are not useful for QTVR work. In addition to sucking battery power, after you get set up, you have little choice of the composition once you start shooting.
For some good information on digital cameras, check out:
or
Short lessons:
1) Shooting indoor panoramas are a real pain. The lighting will make you nuts if you are not aware of the problems. If you want to make an accurate representation of and indoor scene, be prepared to spend many hours and lots of money on lighting alone. The other minor issue is the lens nodal point which must be set much more accurately than what you would need for outdoors work. The correct nodal point setting will prevent parallax between near and far objects as the camera is rotated.
2) Shoot outdoor panoramas as they are the simplest. Let the pros mess with the indoor stuff as they can charge for the headaches.
3) A mono-pod is the best way to shoot a panorama in a crowded area since they set up fast and are non-intrusive. You can make a simple pan/level meter out of a compass and a bubble level which attaches to the pod for accurate imaging of the panorama. Don't use a mono-pod on soft surfaces like sand or snow unless you have a large plate at the base to prevent it from sinking as you rotate around.
4) Always carry enough film and batteries for the job you have in mind. If your digital camera has a power port on it, make yourself a battery belt that can feed the camera power. Never leave these things at the base camp when you go on your hike.
5) When you are having a great time out in the noontime sun shooting your 40 panoramas, remember that you are in the noontime sun having a great time and you may get sunburned.
6) Be sure you have the correct camera settings (exposure and focus) before you begin to waste film. Be sure you have the correct pan head settings before you begin to waste film.
7) Automatic exposure is recommended and is not a terrible thing for taking panoramas. The results are excellent as long as the scene has fairly balanced lighting and you have enough overlap between images (which results in closer exposure settings between images). The other positive thing about auto exposure is that most cameras, digital and traditional, expensive and throwaway, can do it and is one less thing you need to worry about. Autofocussing on cameras with small diameter lenses is of little importance since they all basically focus 16 inches to infinity. Any focus issues will most likely be washed out in the stitching process as the images are matched and morphed together.
8) Click-stop pan heads do not save you time. The time saving aspect is proported to be that you do not need to pay attention to where the next image should be taken - you just "click" to the next spot. The accuracy of a click-stop head is also not needed as long as you have a template with demarcations for all the pan angles and you can rotate to "close enough" of the mark each time. Missing a mark by too much will result in the need to do your stitches interactively.
9) Avoid an interactive stitch, if you can. The results are almost always as good as the little bit of tweaking you end up doing interactively.
10) The top three things you will mess up while taking a panorama
- You will forget if you have advanced the film for this shot
- You will forget if you have imaged this shot
- You will forget if you have rotated the camera for this shot
One solution to this is to always snap the shot immediately after you rotate the camera to the next position. You can then worry about advancing the film or whatever after that. This way you always know the shot is taken for a given position...probably.
11) When shooting underwater, remember lesson #10 and have your dive buddy follow the camera rather than lead it. By leading the camera, you get all the stirred up muck created by their motion in the water. Also make sure they are out of the view of the lens, and therefore the exposure. There is nothing worse than having to paint out a divers head or fins in post. In addition, be sure your tripod is weighted such that it sits firmly on the ocean floor and is not "readjusted" by surge in the middle of a shoot.
12) You can create a panorama with any cheap throwaway camera by holding it close to your eye and rotating around your own body pivot point. The result will probably need to be stitched interactively, but it will work and the results are surprisingly good. At the very least, this is a good way to get a wide partial stitched image at your kool vacation spot without looking like a geek with all your tripods, panorama heads, and L-brackets.
13) The Apollo astronauts did not know about QuickTime VR when they went to the moon, yet some folks have made VR movies of their expedition. The astronauts took 360 degree panoramas while they were on the moon to document their travels, and I'm sure they did not worry about click-stop pan heads or nodal points.
14) PC-card (PCMCIA) Type-III rotating media holds a lot if images and sucks a lot of battery power. PC-card Type-II RAM media holds a lot fewer images, but uses a whole lot less battery power as well.
15) The QTVR authoring tools are very forgiving. Don't get too caught up with getting everything set up with absolute precision.
16) The noontime sun is generally the best time to take outdoor panoramas. Before and after this time, your artistic talents begin to shine if you can create a good panorama.
17) When taking a panorama on a cliff, make sure you can get all the way around the tripod before starting.
18) The only real important tripod setting is to make sure the camera rotates on a plane. Messing this up will result in hard to impossible stitches.
19) Don't forget to carry around the hardware to attach the camera to the tripod.
20) Don't forget to set the camera's ASA film settings before doing an underwater panorama. It does no good to set this after you have done your shoot, and is hard to reshoot in most cases.
21) You can shoot your panoramas from left to right or right to left, it does not matter. You do, however, need to feed the stitcher the images from left to right. You can do this by counting up or down with the "-files" command. For example, if you have 16 images shot right to left and numbered 001 to 016, you would use: -files "016-001" to get the images stitched in the correct order, left to right.
22) A $2000 USD film scanner is a good option if the expense of PhotoCD is too much over the long run.
23) Don't get lost in the technical minutiae - remember that it is possible to create a crude panorama with a bunch video stills smeared together in Photoshop and the free panorama creation tool.
24) Use a nylon mounting bolt (size is 1/4-20 and available at most hardware stores) to mount cameras with plastic mounting threads to your L-bracket. Most consumer digital cameras have plastic tripod mounting threads, so check yours carefully. Using a standard metal mounting bolt will quickly strip the mounting threads on your camera and the repair is non-trivial, if possible at all.
25) The number of exposures per panorama is directly related to the number of exposures on a roll of film. If the number of exposures required for your panorama is 18 and you are using a roll of 36 exposure film, you may get 2 complete panoramas out of the deal. From our experience, you should take two 16 image panoramas and have a few extra exposures available for emergencies. You should never push your film usage to the limit of the exposures on the roll as you will run out of exposures at the worst possible time.
26) Why is it you can not buy a pan only head for your tripod? This is not really a lesson, it is more of a question . You can get pan/tilt/swivel heads, but not a head without the tilt and swivel. This is weird and perhaps there is a market for this. You would think a pan only head would be useful for, say, following the movement of a horse race with a video camera or with a still camera with a fast motor drive. Perhaps the free market has failed us here, or maybe we are the only ones who would want such a thing. And no, the $600 Kaidan head does not count. We want a pan only head similar to what you would get by chopping off the tilt and swivel portion of your average tripod head.
26 - Answer) Why is it you can not buy a pan only head for your tripod? You Can! Kaidan (http://www.kaidan.com) has a product called the KiWi™ (http://www.kaidan.com/kiwi.html) which is simply a pan only head with a built-in L-bracket that works for most camera/lens configurations. The Kaidan KiWi™ is avaialble for around $100 USD.
- 27) Never sharpen or resize with the stitch tool. You should let the stitcher do what it does best, stitch images to form a panorama. Let Photoshop do what it does best, image manipulation. In Photoshop you would do the following:
- Convert the image to LAB mode
- Use the Unsharp Mask filter on the "lightness"
channel only
- Amount = 100%
- Radius = 1
- Threshold = 0
- Convert back to RGB mode
- Perform any color correction, level adjustments, spot removal, whatever
- Resize the image so that the height (the larger dimension) is a multiple of 96
- Use the Unsharp Mask filter on the RGB image
- Amount = 25% to 50%
- Radius = 1
- Threshold = 0
- Save the final panorama image
The Final Lesson
QTVR is great fun and very open to experimentation - don't listen to all the stuffed shirts and the "you are not doing it right" talk. Remember: Necessity is the mother of invention. Creativity has no limits. There is a lot of potential here and it will take some creative and unorthodox minds to free it.
If you have lessons you would like posted, please let us know.
Email: EasyQTVR@OutsideTheLines.comHome - www.OutsideTheLines.com
Questions or comments about this site should be directed to:
SiteGuy@OutsideTheLines.com