Trying to rescale Vvardenfell (I need a 3x sized map of the island in TES lll) and using TESAnnwyn, I met some problems with map enlargement.
I tried to export heightmap from Morrowind.esm in BMP and RAW formats with different bitrate, enlarge it in Photoshop CS6 (and other versions of PS and GIMP and even Paint.NET) using all possible algorithms and import back to the game. But failed because enlargement (and even saving without enlargement) in graphic editors produces numerous gradient overflows/underflows and height problems as a result.
Lightwave created 2x scaled Vvardensfell map for Oblivion by exporting "16-bit RAW image with TESAnnwyn along with the Vertex Colour Map and Texture Placement map. All 3 images have been double-scaled. The heightmap was doubled in Photoshop CS with Bicubic Smoother interpolation and a blur applied twice to help flatten the terrace effect produced by normal bicubic." I tried to repeat all the steps directly and with changes but with no success. And cannot understand now how to solve the problem and get 3x rescaled map without gradient bugs.
Would be glad to hear any suggestions,
Thanks and sorry for poor English.