Render one raster tile and return the image.

Returns the image itself rather than a redirect: the dataset is authorized, then the rendered tile comes back in the response body. Used by the development proxy and by deployments that run without nginx in front.

colormap_name applies a colormap to a single-band raster. Passing gray leaves the rendering unchanged, and a digital elevation model ignores the parameter, because its terrain encoding cannot be recoloured.

stretch chooses how pixel values map to the output range. minmax keeps the range the dataset already implies: the recorded per-band minimum and maximum for a raster imported from a remote source that published statistics, the data range read from band statistics for floating-point data, a range derived from the data type for other integer data, and no rescale parameter for 8-bit data, which needs none. percentile and stddev instead derive a range from band statistics read at request time, for up to three bands. A digital elevation model ignores the parameter, and so does a request whose band statistics cannot be read, which falls back to minmax rather than failing.

pmin and pmax (2 and 98 by default) are read when stretch is percentile, and sigma (2.0 by default) when it is stddev. A parameter that does not apply to the selected stretch is ignored, and its default is used in place of the value sent.

Responds 204 when the tile falls outside the raster, 400 for an unsupported format, 401 when authentication is required, or when a request that no capability authorized carried a credential which did not resolve, 403 when the embed token is invalid or expired or a multi-tenant request arrives with no tenant context, 422 for an out-of-range stretch parameter, and 503 when the renderer cannot be reached. A different failure from the renderer is passed through with its own status.

404 covers more than a missing dataset. A dataset that is unknown, is not a raster or has no image answers 404. Where no capability authorized the request, so does a dataset the caller may not read: an authorization denial on a non-public raster, and an unpublished raster asked for by a caller who is neither its owner nor an admin. That is deliberate, so a refusal keeps a dataset's existence undisclosed.