![]() The 3-D glasses have polarizing filters matching to the projectors’ filters. Light from one projector is polarized in one direction and light from the other is polarized along the perpendicular direction. One projector displays images intended for the left eye, and the other for the right, with a polarizing filter in front of each projector. They align two projectors so images line up on the screen. Digital IMAX theaters use linear polarization. Theaters use two forms of polarization for 3-D movies - linear and circular. Humans aren’t sensitive to light polarization, so image quality isn’t disrupted. That plane - the wave’s orientation - is what we refer to as polarization. Light is an electromagnetic wave traveling along a particular plane. Nowadays, we avoid this problem by using glasses that work with polarization. However, this system depends on color filtering that distorts the movie’s color quality. Shifting in the opposite direction pushes the image back. ![]() Increasing the offset a little, so the left eye’s image goes to the right and the right eye’s image goes to the left, pulls the image out in front of the screen. By drawing the images on top of each other, viewers will see a flat image on screen (the offset between the eyes is zero). Geological Survey - Geology Discipline / Public domain.įilmmakers consider how the degree of offset between these images translates to depth inside our brains. The lenses control what each eye sees by filtering the light going to each eye, only letting certain wavelengths pass. With the glasses back on, your brain merges those images to create the perception of depth. Look at a movie character without the glasses - two outlines extend from the character, identical except one’s blue, the other red, and they’re slightly offset. They approximate the offsets, depending on how far things are, that your eyes expect in life. The glasses recreate that triangulation by feeding distinct images to the eyes. Scientists think that computation occurs in the visual cortex, where individual brain cells seem sensitive to specific distances between the eyes and use those distances to compute depth. ![]() Your brain uses the offset in those views to determine an object’s distance, triangulating between both eyes. Hold a finger in front of your face while covering one eye at a time - the position of your finger jumps. We see the world from two, shifted views, one provided by each eye. How do the “classic” 3-D glasses with the red-blue lenses work? Jenny Read, a vision scientist at Newcastle University explains how filmmakers use the brain’s natural functioning to create the 3-D experience. Most of the technology making 3-D movies work exists inside our skulls. As usual, all this is somewhat irrelevant if it's not a concern to make the map fit a globe, but it's good to be aware of.With 3-D glasses, explosions, gore, or magical creatures jump off the screen. It's very easy and fast, and gives you a way to swiftly check what the actual planet would look like. That said, I also recommend making it a habit to regularly load your map into Map to Globe to check how it looks in 3d (for this, the map needs to be in the equirectangular projection). The official one is 7500x3750, although I've only been able to use 6800x3400 without crashing the program. Although I should note that there are some resolution limits with GProjector. With GProjector, choose Equirectangular Oblique projection, and then you can specify where you want the map to be centered (default latitude is 0 N, you can change this to 90 N to center the map on the North Pole, save it and do your mapping, then reload into GProjector and input -90 N to change it back to the original). GIMP also has a feature called Polar Coordinates (Filters->Distorts->Polar Coordinates) that you can use, although it unfortunately tends to make things a bit blurry (whereas this is not the case with GProjector, so I recommend using the latter for this). I've considered taking out the poles on the top and bottom, mostly because I don't know how to shape it to resemble an actual land mass on the globe projection.The easiest way is to just use GProjector to essentially move the pole to the equator, then you can easily map it as you would normally, and just switch the pole back (again, using GProjector). I'm still just learning how to make a map in general. However, I'm not terribly concerned at this point making it perfect to a globe, at least not yet. Thanks for the feedback! I should redo the coloured map to the projection scaling.
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