Currently it is possible to edit a non-existing elevation tile, i.e. one that is displayed as a sub-area of an ancestor tile. Edits go to the ancestor, but don't work properly and corrupt the tile.

Instead, editing the ancestor should not be allowed at all.
The user should be warned, and offered the option to create the tile before editing. This also requires the ability to create a new elevation tile as an interpolated ancestor sub-area, which is not yet implemented.

Propagation of imported patch to lower resolution levels is applied even if not selected by the user.

Show a colourbar below each tile type instead of just the Elevation and Elevation_mod layers.

In addition to displaying a single tile at a time, allow display of 2x2 blocks, to make it easier to edit across tile edges.

To prevent quality degradation of surface tiles across edit cycles, save any edited or imported tiles in a temporary directory as PNG files and load these for further edits.

Upon committing a tile, save it as DXT1 in the Surf layer (but optionally keep the PNG versions to allow further edits.)

To bring in line with the Orbiter toolchain.

Provide user help content for tileedit functions.

Provide interface to set the mapping from elevation data to 16-bit greyscale values.
Modify the vmin and vmax output in the metafile to define that mapping compatible with ele2png.

• Importing a patch for surface tiles which don't exist yet does not work correctly.
• Propagating an imported patch to non-existent ancestors also fails.

Correct behaviour should be to create new tiles as required. Before import, the required tiles should be synthesized by interpolating an ancestor so that alpha-blending and colour-matching functions can be applied.

Exporting elevation tiles to PNG makes it easier to edit using image editors.

Export either to single-channel 16-bit data, or to 3-channel 8-bit RGB data using a fixed LUT.
Tile scale and offset values should be stored as custom tags in the PNG file.

• Show colourbar
• enable interactive selection of elevation display range
• interactive selection of colourmap

Matlab-based code isn't ideal since for developers it requires a Matlab license to compile, and for users it requires installing the bulky Matlab runtimes.

I am migrating tileedit to Qt to avoid these problems. Initially this should just replicate the Matlab functionality.

Matlab implementation is moved to "matlab" subdirectory. The Qt implementation sits alongside in the "qt" branch.

Allow surface tiles to be created from png images. Essentially a replication of the plsplit functionality. No export support to be added though since the lossy DXT1 data format used for storing surface tiles would lead to data degradation on export-import cycles.

Enable tileedit to extract tiles from compressed .tree files

Surface tiles for levels 1-4 (i.e. up to the root of the quadtree) are required for for opening in tileedit. If missing, tileedit crashes. This should be handled more gracefully.

User options and directories should be remembered across sessions.

In addition to the full "Elevation" display option, provide an option to display the "elevation_mod" layer on its own.