Comparison of Dolly and Zoom - Page 2

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Comparison Two: Distorted Perspective in the Center of the Screen

Note: Edge-to-edge thumbnails don't really illustrate the problem very well. So for each pair of screenshots, please download both images into an empty folder. Then preview one of them, maximize the window, and press the "Next image" button repeatedly to flip back and forth between the two.

The vert - effect is basically zooming in. Because dollying out is often mistaken for zooming out, some may think that dollying out is a good hor + solution for games that are vert -, because dollying out will cancel out the zooming in. This is incorrect; if you zoom in and dolly out at the same time, your perspective becomes distorted, as objects that are far away appear closer than they actually are, while objects that are already close seem to stay where they are. This effect was famously used in the film Vertigo in order to disorient the audience, but disorienting the players is not a good way to make a game support widescreen better.

First, a pair of screenshots with the FOV and cg_cameradist settings left at default. The first is standard, the second is widescreen.


This is vert-, and it is zoomed in. In the widescreen shot, Julie appears closer to the camera, and the ledge also appears closer to the camera. But the apparent distance between Julie and the ledge remains the same; no perspective distortion is evident.

Now let's look at another pair. The first shot is the same as before. The second one has an increased FOV, zoomed out to 100.39.


The zooming out (increasing the FOV) cancels out the zoom in perfectly. Both Julie and the ledge appear to be the same distance from the camera as before, making the game hor +.

Now one more pair, to show what happens when you don't adjust the FOV in the widescreen picture, but you do pull the camera back, effectively zooming in and dollying out at the same time (Vertigo effect):


Thanks to dollying out, Julie appears to be the same distance from the camera in both screenshots. For her, zooming in and dollying out have canceled eachother out. But look at the ledge! It appears to have moved CLOSER in the widescreen shot. By dollying out, the apparant distance between Julie and the cliff has decreased, even though the actual distance has not. This is indicative of a distorted perspective, and as a result, a player is more likely to underestimate the distance necessary to clear the jump.

Comparison Three - Indoors

You can't dolly out as far indoors as you can outdoors. In some situations, even the default camera distance is farther than you can go. And there are even situations outdoors where your back might be against a wall or a tree. Attempting to increase the camera distance in these situations will have no effect. Zooming out, on the other hand, works indoors or out.