Canon Camera Hackers Manual

Contents

200 C H A P T E R 6 Advanced Techniquesf The same features in Autopano Pro are available in PTGui—one of thepioneers of panorama technology.f Hugin, which doesn’t lack in power, is the free Open Source alternativefor panorama stitchers. It supports HDR panorama stitching and canalso be used for nonpanoramic purposes, such as perspective correctionof architectural shots.All panorama stitchers allow you to choose among different projections. Aprojection is responsible for how the image pixels are mapped onto theviewing surface—i.e., how they are projected. All programs support at leastrectilinear, cylindrical, and spherical projection. Some of them supportmany more and even rather exotic projections.f The rectilinear projection simply projects the whole panorama onto aflat surface. Because this leads to strong distortions towards the edgesof the image (similar to a photo taken with an ultra-wide-angle lens),the maximum angle of field should be limited to 120°.f The cylindrical projection projects the panorama onto the inside of acylinder that is then unrolled onto the viewing surface. This projectionand its variants (e.g., Miller projection) are best suited when you want toprint panoramas with a wide angle of field.f The spherical or equirectilinear projection projects the panorama ontothe inside of a sphere that is then unrolled onto the viewing surface.This projection is typically used for spherical panoramas viewed on acomputer display using interactive viewers.Viewers for spherical panoramas are available as a Java applet or as a Flashapplication. Apple Quicktime can show panoramas, too. Among the Java-based viewers, the free PTViewer is interesting. It can handle cylindrical andspherical projections and also display true HDR panoramas (see next sec-tion) with the full contrast range. When the user changes the angle of view,the viewer will adapt to the brightness of the scene, much as the humaneye would do. For Flash, there are many commercial offerings for panoramaviewers plus the notable exception of the panoSalado viewer that comesfor free.6.2 HDR PanoramasWe have already mentioned one of the problems in panorama photogra-phy: the large scene contrast. When the sun is shining and the angle ofview is 180° or greater, you will have images that are shot with the sun inthe back and images shot straight into the sun. But contrast at night canalso be too high for a classical exposure.