Hi all !
Now you can use render engine from Æsir game client to view maps.
Just download it from there(use version >= v0.3.2) : https://cloud.acomirei.ru/s/khm08qmHJSVLEUy
Extract it somewhere, put grfs near executable and edit their names in the aesir.json.
Then click viewer.bat and it will show you the map.
You can hide settings using F12.
Render quality and antialiasing requires restart.