Frequently Asked Questions about Panorama Tools 1. General Questions 1.1. Why do I get Cropped Images? 1.2. How do I get the Whole Image? 1.3. What is the HFOV? 1.4. What is, and when do I need the VFOV? 1.5. Why is Panorama Tools so slow? 1.6. How to batch convert Images 2. Questions about Correct 2.1. How do I correct Barrel Distortions? 2.2. Can 'Correct' be used as Center filter? 3. Questions about Remap 3.1. What do all these Cryptic Words mean? 3.2. How do I edit and retouch a part of a Panorama? 3.3. How to edit the zenith in a Spherical Panorama? 3.4. How do I convert from LivePicture format to QTVR and vice-versa? 4. Questions about Adjust/ Stitching 4.1. Can Panorama Tools stitch images? 5. Questions about Perspective 5.1. How to perform y-axis stitching of images 1. General Questions 1.1. Why do I get Cropped Images? The plug-in interface of Photoshop does not allow to change the size of images which is required by some Panorama Tools. If the resultimage is equally sized (eg most transformations in the 'correct' submenu), it simply replaces the source image. If the resultimage is larger or smaller than the source, you can set options how Panorama Tools should handle this situation by clicking the 'pref' button, which each tool displays. You can select among the options: (a) display cropped/framed version of resultimage. This image replaces your source image. Please note that you not only loose image information, but also some image characteristics: The horizontal field of view changes! Other than that it is the most convenient mode, and default. (b) create a temporary file which holds the total resultimage. You can select place and name for this file. Panorama Tools adds a unique identifier and the extension '.tif' to this name. (c) Open this file using any suitable program to display the result. On the Macintosh this is always the currently running Plug-in host, so to the user it looks as if the result were returned by the filter. On the PC this works with some plug-in hosts (Photoshop 4, Picture Publisher 6) but not with some others (Paint Shop Pro). In this case you have to select another application to display the result (the file format is TIFF). For this option to work, you have to check (b) also! GraphicConverter can handle size changes, and thus displays only option (a) and (b), (b) not creating a file, but displaying the full-sized result. 1.2. How do I get the Whole Image? See 1.1 (b) and (c). 1.3. What is the HFOV? The horizontal field of view is the angular coverage of your lens in horizontal direction. Don't confuse with FOV-values from lens data, which usually refer to diagonal coverage. The general formula for rectilinear lenses is HFOV = 2 * arctan( (image width/2) / (focal length) ) Image width and Focal length should be given in the same unit. This leads to the following data for 35mm equipment: ***************************** Field of View Table **************************** * * * Focal Length HFOV / Landscape HFOV / Portrait * * * * 8mm Fisheye 180 180 * * 15mm Fisheye 130 90 * * * * 15mm Rectilinear 100 77 * * 17mm Rectilinear 93 70 * * 20mm Rectilinear 84 62 * * 24mm Rectilinear 74 53 * * 28mm Rectilinear 65 46 * * 35mm Rectilinear 54 38 * * 50mm Rectilinear 40 27 * * * ****************************************************************************** This is the single most important parameter used by many calculations. Please note, that cropping an image horizontally changes HFOV! 1.4. What is, and when do I need the VFOV? The vertical field of view is the angular coverage of your lens in vertical direction. In almost all cases Panorama Tools calculates this value internally by using HFOV, lens type and image size, ie to change VFOV you should adjust image height. Only one remap transformation (fisheye-vert - to - panorama) requires a valid entry for VFOV; it is ignored in all other cases. 1.5. Why is Panorama Tools so slow? Panorama Tools uses a high quality bicubic interpolator and does all math in floating point format. 1.6. How to batch convert Images Panorama Tools is not scriptable, but can be used for batch conversions using Photoshop's 'Last Filter' command in an action set. A sample action containing just this command is included in the distribution. To use it be sure to have the 'Last Filter' menu item in Photoshop set to the Panorama Tool you want to use. In GraphicConverter, you can use Panorama Tools in the 'Convert More...' menu to do batch conversion. Please notice that Panorama Tools does not display the ususal progress bar while batch converting inside GraphicConverter. You can still interrupt by pressing 'cmd-.' 2. Questions about Correct 2.1. How do I correct Barrel Distortions? Correcting barrel (and pincussion) distortions is accomplished using the 'Radial-Shift' submenu. Try the parameters a=0; b=-0.01; c=0; d=1.0 (same for all colours) on a testimage (positive 'b' for pincussion distortion), and compare it with the original. Change the value of 'b' until you are satisfied. Next: change d to get a+b+c+d=1. This way image size stays the same while correcting. You can save your settings and reuse them on other images. Please note that landscape and portrait format of the same lens need separate corrections. The parameters 'a' and 'c' are only needed in unusual cases (eg combined pincussion/barrel distortions etc). 2.2. Can 'Correct' be used as Center filter? The 'Radial-luminance' tool provides an electronic center filter. You should enter a pixel value which refers to the difference (determined by the eye-dropper tool) between (supposedly) equal pixels in the center versus edge. Panorama Tools will darken the center and brighten the edges to bring luminance to the same value. The Radial Luminance tool simply adds and subtracts the appropriate correction to the actual rgb-values. If you have large changes to correct, this might lead to slight colour changes. In this case I suggest to change the image to 'Lab' colour space, and apply the Radial Luminance tool only to the 'L' channel (which unfortunately is still labeled 'Red' inside 'Panorama Tools'). 3. Questions about Remap 3.1. What do all these Cryptic Words mean? The various projections 'Remap' is able to handle derive from several formats and lens types. I have changed the menu entries several times now, but it still causes some confusion. (a) normal (rectilinear) is the projection delivered by most camera lenses. The original view of the scene is recovered when viewing this image on a flat surface or screen. (b) QTVR panorama is the projection used by Apple's QTVR-technology and also by LivePicture's 'Cylinder' panos. It is also created by 'Scanning Slit' type panoramic cameras like the Noblex, Horizon, Widelux, Roundshot, Cirkut cameras, or their digital counterparts PanoScan etc. The original view of the scene is recovered when viewing the image on a cylindrical surface from inside. (c) PSphere, or equirectangular, is another cylindrical projection, which in contrast to (b) is able to handle 180 degree field of view vertically. It is used to create sphercial panoramas (LivePicture 'Sphere' mode). It is also used by map-makers to visualize the surface of the earth. (d) Fisheye horizontal (formerly Fisheye TP) is a fisheye image with the camera aimed horizontally. (e) Fisheye vertical (formerly Fisheye CP) is a fisheye image with the camera aimed vertical. Both fisheye transformations assume so called 'f*theta' projection. They recover the original view when projected onto a spherical screen. (f) Convex mirror is the image created by a spherical image (looking into a christmas ornament). It is similar but not identical to the case (e). 3.2. How do I edit and retouch a part of a Panorama? With Panorama Tools you can edit portions of any panorama using Photoshop or any Graphics program (eg add text or other features) and rewarp the portion to seemlessly fit back into the panoramic image. This works for both QTVR and LivePicture panos (or any other photographic panorama) provided you have an image to work on (the QTVR-movie has to be converted to an image first!). Follow these steps: (a) Select a vertically centered piece from your panoramic image to work on. Copy this portion to a seperate image. (b) Determine the HFOV-angle of this portion using the formula HFOV = 360 * (width of portion)/(width of pano) (c) Convert the part to 'Normal' using the 'Remap' tool with settings from: QTVR panorama (or 'PSphere' if you are using LivePicture Sphere mode) to: Normal HFOV: see (b) VFOV: 0 (ignored) The preferences should be set to option (b) (see the Readme file) because you need the whole converted image. Now do your editing, but be sure to not change image size. Then convert back, and reinsert into your panorama. 3.3. How to edit the zenith in a Spherical Panorama? This is the most difficult part of a spherical panorama, and can not be edited in the original 'PSphere' mapping (you can try, but it probably will not fit very well). Solution: Take the upper half of your spherical panorama, and convert to fisheye format using the 'Remap' tool: from: PSphere to: Fisheye Vertical HFOV: 360 VFOV: 0 (ignored). The 'pole' is now in the center of your image, and can be easily edited. Later, convert back using either the opposite transformation (Note, that HFOV of the fisheye image is only 180 degrees!), or use the 'Adjust' tool with 'yaw' set to 90 degrees. Insert the transformed piece into your original image. 3.4. How do I convert from LivePicture format to QTVR and vice-versa? For all transformations, set the preferences options to (b) (see the Readme file). To convert from QTVR to LivePicture 'Sphere' mode: from: QTVR panorama to : PSphere HFOV: 360 VFOV: 0 (ignored) To view the RealVR image, you have to add stripes at the top and bottom to expand the image to 1:2 aspect ratio. To convert from LivePicture 'Sphere' mode to QTVR-panorama: QTVR doesn't allow 180 degree vertical field of view, as LivePicture 'Sphere' provides. You first have to cut two stripes from top and bottom of the spherical image to reduce aspect ratio below 1:2 (It is up to you how much you cut; the QTVR pano will be very large if you cut only small stripes). Then use the settings: from: PSphere to: QTVT panorama HFOV: 360 VFOV: 0 (ignored) The converted image has to be run through one of Apple's tools (eg MakeQTVRPanorama) to make the movie file.
4. Questions about Adjust/ Stitching 4.1. Can Panorama Tools stitch images? Yes. The program creates a full 360 x 180 degrees spherical panoramic image from any set of input images. The output can be directly used for LivePicture panos, or (after conversion, see FAQ 3.4) for QTVR-panos. The user has to provide the following information for the final panorama: - width in pixels and for each input image: - image type (which lens and HFOV) - image position in pano (pitch/roll/yaw angles). See the PDF-information included in the distribution.
5. Questions about Perspective 5.1. How to perform y-axis stitching of images The images need to be corrected so that the film-plane for the two images is parallel. This can be done using the 'perspective' tool: Suppose your upper image is made at 20 degree tilt, and the lower at -20 degrees. Open the upper image in PS, select 'perspective' and set Format: normal HFOV: the horizontal field of view of your lens (see Readme file for table and formula). Turn to: horizontal 0 vertical -20 Click 'Degrees' Rotate: 0 Push 'Source' to set width and height identical to source image. Click 'OK' and your image will be converted. Do the same with the lower image, but set vertical to +20. Now merge these images in PS.