horizonator.docstring

Rendering of SRTM terrain from Python

SYNOPSIS

    import horizonator
    import cv2

    h = horizonator.horizonator(34.2884, -117.7134,
                                3600, 450)

    (image, ranges) = h.render(-40, 100)

    print(image.shape)
    ===> (450, 3600, 3)

    print(ranges.shape)
    ===> (450, 3600)

    cv2.imwrite("iron-mountain.png", image)

The horizonator tool renders SRTM topography to simulate views at any location
where this data is available. The general call sequence is

- h = horizonator.horizonator(...)
- h.render(...)
- h.render(...)
- h.render(...)

The constructor loads the DEMs centered around some point, and each render(...)
call produces images based on looking at those DEMs from different locations.
The constructor is relatively slow, and the render(...) calls are relatively
fast.

ARGUMENTS

The __init__() function takes

- lat, lon: the latitude and longitude of the center point, around which the
  DEMs are loaded. Initially the camera is positioned at this center point, but
  this may be moved around with each subsequent render() call

- width, height: the dimensions of the images we will be producing

- render_texture: optional boolean, defaulting to False. if not render_texture:
  we color-code the resulting image by distance. If render_texture: we use
  openstreetmap tiles to texture the image

- SRTM1: optional boolean, defaulting to False. By default we use 3" SRTM data.
  Currently every triangle in the grid is rendered. This is inefficient, but the
  higher-resolution 1" SRTM tiles would make it use 9 times more memory and
  computational resources, so sticking with the lower-resolution 3" SRTM data is
  recommended for now

- dir_dems: optional string, defaulting to "~/.horizonator/DEMs_SRTM3". The path
  to the .hgt files containing the SRTM DEMs

- dir_tiles: optional string, defaulting to "~/.horizonator/tiles". Ths
  OpenStreetMap tiles are downloaded and stored here.

- allow_downloads: optional boolean, defaulting to True. If True: we try to
  download missing OpenStreetMap tiles.

- radius: optional integer, with some reasonable default. Specifies the size of
  the DEM to load. This many cells are loaded to the N, S, E and W of the viewer.