Efficient generation of terrain openness

A non-transitory computer-readable storage medium storing computer program instructions executable by one or more processors to perform operations for efficiently rendering a texture, the operations comprising:

• for pixels of a texture of a digital elevation model, where the pixels encode elevations pertaining to locations in a first geographic area, where the digital elevation model further comprises at least part of a plurality of mipmap levels which encode elevations:
• determining an openness factor based at least in part on elevations at one or more pixels of the mipmap levels and performing at least one linear interpolation using at least one fractional pixel value;
• and
• rendering an electronic map corresponding to the first geographic area using the openness factor of the pixels of the texture.

A method for efficiently rendering a texture, the method comprising:

• for pixels of a texture of a digital elevation model, where the pixels encode elevations pertaining to locations in a first geographic area, and where the digital elevation model is arranged as a grid and further comprises at least part of a plurality of mipmap levels which encode elevations:
• determining an openness factor based at least in part on elevations at one or more pixels of the mipmap levels and, for each direction of a plurality of directions on the grid from a pixel:
• determining a greatest elevation among a plurality of pixels in the direction, where at least one pixel of the pixels in the direction is from at least part of a mipmap level;
• determining an angle based on the elevation of the pixel and the greatest elevation;
• and
• averaging the determined angles;
• and
• rendering an electronic map corresponding to the first geographic area using the openness factor of the pixels of the texture.