Creating a QuickTime Virtual Reality image, video, or object allows users to easily understand and to have an accurate view of the given image, video, or object. It can allow for either a very small web-friendly file or a very high definition demonstration file.
A QTVR is a panoramic image that can be panned or zoomed around in using a QuickTime web plug-in or stand-alone player. QTVRs are created by taking pictures while rotating and tilting the camera around a single point. This captures enough image data to allow for a 720° shot to be compiled. (A slight play on words- 360° plus 360° equals 720°.)
In order to make a QTVR you will need the following:
• Access to StitcherUnlimited • A panoramic tripod head and quick-pan rotator base. • A tripod. • Any familiar digital camera. (Make sure it has memory and is charged!) • A small flathead screwdriver. • A small place marker (coin, St. Olaf ID card, etc.)
This website showcases some of the QTVRs St. Olaf MDC students have created. Shift will allow you to zoom in, and control will allow you to zoom out.
Make sure your hardware is ready to go- this means making sure that the pano-head the camera will be rotating on is set up correctly. Depending on the focal length of the camera lens that you will be working with, (the smaller the focal length, the more the camera can take in with one shot) different amounts of rotation are required to get all of the shots. A rule of thumb is to have a 50% overlap between each image, so use the following table to determine the number of pictures you will have to take on a row in order to get sufficient coverage.
Lens (mm) # of Images (MDC fisheye for Digital Rebel) 15 10 (MDC Digital Rebel normal lense full zoom out) 18 14 (MDC Digital Rebel medium zoom) 24 18
Changing the lens to a smaller focal length or zooming out reduces the number of pictures you have to take, the time it will take Stitcher to render the pictures, and the space that all of your pictures take up. At the extremes (a fisheye lens, for example) you will only have to take a handful of pictures on each row- the downside is that you will have to correct for the distortion during post-production.
In order to change the number of images that you take on a row, the small dial that rests inside the pano-head will have to be swapped out. This is a simple procedure- the dials look like this.
You will have to drop the bottom piece of the pano-head off and swap out the dials. If you have it set up correctly, turning the pano-head will make a “click” noise every time it rotates the appropriate number of degrees.
The pano-head is very adjustable- it is able to accommodate almost any camera. In order for Stitcher to process the pictures you are going to take, the camera cannot move during the photo shoot. You will need to make sure that the tripod and pano-head are adjusted and locked in. When putting the camera upon the pano-head, the nodal point of the lens needs to be resting directly above the very center of the tripod. If the nodal point is off center, there will be parallax errors when trying to stitch. (Parallax error is when you rotate the camera and distant objects appear to shift from picture to picture. This is a subtle error, but it makes it difficult for Stitcher to determine how to stitch two photographs together.) However, it is difficult to determine the exact location of the nodal point of the lens, so you will have to do a little guess work.
The nodal point is approximately here:
Try to center that point directly above the center of your tripod- you may have to adjust the pano-head forward and backward.
Loading your photographs into Stitcher is simple- the five icons on the left side of the screen will be suitable for doing a majority of the tasks we need to do. Click on the uppermost icon or use the hotkey command-l, and select your photographs (click the top picture, hold down shift, and click on the bottom picture to select them all at once). After they are loaded, they may need to be rotated so that they are upright. Press command-a to select all of the photos that have been loaded, and use the drop down menus at the top of the screen to rotate the images appropriately (Edit-> Rotate-> Rotate XX°).
Moving around Stitcher:
Holding command while dragging the mouse around will allow you to zoom in and out of the panorama. Holding option will allow you to pan around your panorama. Clicking an image you have loaded into the panorama and pressing the equal key will reorient the Stitcher window with that image as the center.
After your pictures are ready to be stitched, we will have to calibrate Stitcher for any distortion that may have occurred in the photography process. Simply take a photo from your middle row of pictures (the one you started with, at 0° tilt) and drag it from the image strip at the bottom of your screen to the main window. Now, take the next picture from your strip, and overlay it on top of the first picture so that all of the corresponding features from each photo are on top of each other. If you are having difficulty doing this, you may have to rotate the second photo a bit to get it to fit better. In order to do this, hold down shift and control and click the picture while dragging in the direction you would like it to rotate. The location you click will be the rotational axis, so if you match up some very easily identifiable object in each picture so that the corner or one small point is aligned, you can use that corner or small point to rotate around until the rest of the image becomes aligned as well. Once you have your two images aligned, use the drop down menu to calibrate high distortion (Tools-> High Distortion-> Calibrate).
To stitch the rest of your photos, select an entire row from your image strip (holding shift lets you pick multiple images) and click on the second icon from the column of five to begin automatically stitching. The computer will now figure out where each photo goes. It is possible to try and stitch all of the photos at once, but in the event that Stitcher makes a mistake, it is fairly difficult to rectify without making the finished result look very strange. I suggest automatically stitching a row at a time, starting with your 0° row.
Closing the Panorama:
The most difficult part for Stitcher to figure out is how to “close” the panorama, or how to make the complete circuit of photos. Sometimes the only way to close the panorama is to do it yourself. If this is the case, it is easier to work with the panorama spread apart so you can tell where it was not able to close the circuit. In order to do this, you will have to tell hold down shift and press the plus key. This will stretch out your stitched panorama, and you should be able to clearly see where it needs to be closed. Once you have found the two photos that need to be stitched to close the panorama, click on one of them, and then mouse over the second icon out of the five. This should make seven icons pop up, and you want the one furthest to the right. Click that icon, and then drag and align the two sides of your panorama that need to be closed. In the event that you cannot get it to stitch, sometimes it is easier to choose a different spot for the panorama to be closed. You may have to detach some images around your panorama and manually stitch (delete to detach, enter to stitch) them together until you have changed the location of the gap in your panorama. Try to make the gap between two images with lots of overlapping unique features- a blank white wall, as a counter-example, would not work very well.
Simply rotate the Stitcher window so that you are facing the top and drag your 90° image onto the panorama. You will likely have to rotate it to get it fit right (shift + control) and manually stitch it (enter).
Capstone (Bottom) and Stencils:
Getting a good-looking bottom is a more difficult task. First, you will have to tell Stitcher to ignore any of the tripod that might have gotten picked up in the lowest row of images. Click on a picture that has a piece of the tripod in it, and use the drop down menu to turn on the stencil overlay. With the stencil overlay (Tools-> Stencils), you can create polygons over an image and anything within the polygon will not be rendered when the QTVR is compiled. In order to make a polygon, double click once to get started, and then click once at each of the vertices of your polygon. Finally, when you are on your final vertex of the polygon, double click to close it off. If you are unhappy with your stencil (try to make it as small as possible) you can move the entire polygon as a whole, or any of the individual vertices. You can also delete a given vertex (or the whole stencil) by simply clicking what you would like deleted, and pressing the delete key.
Now, go through every picture on the bottom row with some tripod showing, and stencil out all of the tripod artifacts out of the panorama. When this is complete, you can drop your bottom on with a manual stitch (enter). If this doesn’t work (it won’t stitch, and suggests you force stitch) you may have to retouch things in Photoshop in order for them to look right.
Equalizing and Aligning the Horizon:
Hopefully, you have a complete panorama, and now it can be rendered into a QTVR. You will need to equalize all of the images so that they don’t blend poorly during the rendering process. Press command-e or hit the fourth of the five icons to equalize. You must now align the horizon of the panorama so that when you rotate the QTVR it looks right. In order to do this, click on the third of the five icons.
Rendering the QTVR:
First, make a decision as to where you would like your QTVR to default to when it is opened. In order to do this, just maneuver Stitcher to look at where you would like the QTVR to open. You may need to align the horizon again if you have misaligned anything. Next, click on the fifth icon in the column or use hotkey command-r. Select a name for your final QTVR, and underneath that, select cubic QTVR. Now, you must decide how high resolution you would like your QTVR to end up. If you make it high resolution, you will be able to zoom in and maintain crispness, but it will be a very large file. If it is lower it will render much faster and be more web friendly because of its smaller file size, but you will lose crispness. For the QTVRs on the virtual tour, the resolution used was between 600 to 800 for width and height. Use the slider or enter the numbers manually to select what you would like. Next, click on the QT Movie Settings tab in the Render window. This is where you decide how large the QuickTime movie window will be. This has nothing to do with resolution- you could have a ten thousand pixel wide window, but if you rendered the QTVR with a low resolution, it will still be low resolution, just with a huge window. As a rule of thumb, avoid making the window larger than the resolution you are going to render your QTVR at. If you would like it to appear widescreen, make the width:height ratio 16:9. If you would like it to appear full screen, make the ratio 4:3. Keep the Pan values at -180, 0, and 180. Keep the Tilt values at -90, 0, and 90. Keep the Fov values at 5, 45, and 120. These values work well for 720° QTVRs. Changing them restricts the user from looking at the whole of your QTVR. Finally, after everything has been set up, click the render button. Congratulations! Wait for your QTVR to render, and check out the finished the product.
- http://www.panoramas.dk - A collection of superbly done QTVRs
- http://www.stolaf.edu/virtualtour - St Olaf's virtual tour, which includes many QTVRs
- http://manuals.info.apple.com/en/QuickTimeVR_AuthoringStudioUserManual.pdf - Apple's QTVR manual
- Apple's reference library entries on QTVR