diff --git dataobj/environment.cc dataobj/environment.cc
index 4d9cc36316..ac237e6586 100644
--- dataobj/environment.cc
+++ dataobj/environment.cc
@@ -17,7 +17,7 @@ void rdwr_win_settings(loadsave_t *file); // simwin
 
 sint8 env_t::pak_tile_height_step = 16;
 sint8 env_t::pak_height_conversion_factor = 1;
-bool env_t::new_height_map_conversion = false;
+env_t::height_conversion_mode env_t::height_conv_mode = env_t::height_conversion_mode::linear;
 
 bool env_t::simple_drawing = false;
 bool env_t::simple_drawing_fast_forward = true;
@@ -478,8 +478,18 @@ void env_t::rdwr(loadsave_t *file)
 		file->rdwr_str( default_theme );
 	}
 	if(  file->is_version_atleast(120, 2)  ) {
-		file->rdwr_bool( new_height_map_conversion );
+		if(  file->is_version_atleast(121, 1)) {
+			sint32 conv_mode = height_conv_mode;
+			file->rdwr_long( conv_mode );
+			height_conv_mode = (env_t::height_conversion_mode)::clamp(conv_mode, 0, (int)env_t::height_conversion_mode::MAX_MODES);
+		}
+		else {
+			bool new_convert = height_conv_mode != height_conversion_mode::legacy_small;
+			file->rdwr_bool( new_convert );
+			height_conv_mode = new_convert ? height_conversion_mode::legacy_large : height_conversion_mode::legacy_small;
+		}
 	}
+
 	if(  file->is_version_atleast(120, 5)  ) {
 		file->rdwr_long( background_color_rgb );
 		file->rdwr_long( tooltip_color_rgb );
diff --git dataobj/environment.h dataobj/environment.h
index 02f8dcb129..d681ecf61f 100644
--- dataobj/environment.h
+++ dataobj/environment.h
@@ -325,8 +325,16 @@ public:
 	/// Only use during loading of old games!
 	static sint8 pak_height_conversion_factor;
 
-	// load old height maps (false) or use as many available height levels as possible
-	static bool new_height_map_conversion;
+	enum height_conversion_mode
+	{
+		legacy_small, ///< Old (fixed) height conversion, small height difference
+		legacy_large, ///< Old (fixed) height conversion, larger height difference
+		linear,       ///< linear interpolation between min_/max_allowed_height
+		clamp,        ///< Use 1 height level per 1 greyscale level, clamp to allowed height (cut off mountains)
+		MAX_MODES
+	};
+
+	static height_conversion_mode height_conv_mode;
 
 	/// use the faster drawing routine (and allow for clipping errors)
 	static bool simple_drawing;
diff --git dataobj/height_map_loader.cc dataobj/height_map_loader.cc
index 014eb3e5a1..7784cf00e9 100644
--- dataobj/height_map_loader.cc
+++ dataobj/height_map_loader.cc
@@ -3,246 +3,393 @@
  * (see LICENSE.txt)
  */
 
-/* code for loading heightmaps */
-
-#include <stdio.h>
-#include <string.h>
-#include <stdlib.h>
+#include "height_map_loader.h"
 
 #include "environment.h"
-#include "height_map_loader.h"
+
 #include "../simio.h"
 #include "../sys/simsys.h"
+#include "../simmem.h"
+#include "../macros.h"
+
+#include <cstdio>
+#include <cstring>
+#include <cstdlib>
 
 
-height_map_loader_t::height_map_loader_t(bool new_format):
-		height_map_conversion_version_new(new_format)
-	{
+height_map_loader_t::height_map_loader_t(sint8 min_height, sint8 max_height, env_t::height_conversion_mode mode) :
+	min_allowed_height(min_height),
+	max_allowed_height(max_height),
+	conv_mode(mode)
+{
 }
 
 
 // read height data from bmp or ppm files
 bool height_map_loader_t::get_height_data_from_file( const char *filename, sint8 groundwater, sint8 *&hfield, sint16 &ww, sint16 &hh, bool update_only_values )
 {
-	if (FILE* const file = dr_fopen(filename, "rb")) {
-		char id[3];
-		// parsing the header of this mixed file format is nottrivial ...
-		id[0] = fgetc(file);
-		id[1] = fgetc(file);
-		id[2] = 0;
-		if(strcmp(id, "P6")) {
-			if(strcmp(id, "BM")) {
-				fclose(file);
-				dbg->error("height_map_loader_t::load_heightfield()","Heightfield has wrong image type %s instead P6/BM", id);
-				return false;
+	hfield = NULL;
+
+	FILE *const file = dr_fopen(filename, "rb");
+	if(  !file  ) {
+		dbg->error("height_map_loader_t::get_height_data_from_file()", "Cannot open heightmap file");
+		return false;
+	}
+
+	char id[3] = {0, 0, 0};
+	// parsing the header of this mixed file format is non-trivial ...
+	if(  fgets(id, 3, file) == NULL  ) {
+		fclose(file);
+		dbg->error("height_map_loader_t::get_height_data_from_file()", "Cannot read magic number");
+		return false;
+	}
+
+	const bool is_bmp = strcmp(id, "BM") == 0;
+	const bool is_ppm = strcmp(id, "P6") == 0;
+
+	if(  !is_bmp  &&  !is_ppm  ) {
+		fclose(file);
+		dbg->error("height_map_loader_t::get_height_data_from_file()", "Unsupported height map format (must be bmp or ppm)");
+		return false;
+	}
+
+	const char *err = NULL;
+	if(  is_bmp  ) {
+		err = read_bmp(file, groundwater, hfield, ww, hh, update_only_values);
+	}
+	else {
+		err = read_ppm(file, groundwater, hfield, ww, hh, update_only_values);
+	}
+
+	// success ... (or not)
+	fclose(file);
+
+	if(  err  ) {
+		dbg->error("height_map_loader_t::get_height_data_from_file()",
+		           "Error while reading %s file: %s", is_bmp ? "bmp" : "ppm", err);
+
+		if(  hfield  ) {
+			free(hfield);
+			hfield = NULL;
+		}
+	}
+
+	return err == NULL;
+}
+
+
+const char *height_map_loader_t::read_bmp( FILE *file, sint8 groundwater, sint8 *&hfield, sint16 &ww, sint16 &hh, bool update_only_values )
+{
+	uint32 l;
+	uint16 s;
+
+	if(  fseek( file, 10, SEEK_SET ) != 0  ||  fread(&l, sizeof(uint32), 1, file) != 1  ) {
+		return "Malformed bmp file";
+	}
+	const uint32 data_offset = endian(l);
+
+	if(  fseek( file, 18, SEEK_SET ) != 0  ||  fread(&l, sizeof(sint32), 1, file) != 1  ) {
+		return "Malformed bmp file";
+	}
+	sint32 w = endian(l);
+
+	if(  fseek( file, 22, SEEK_SET ) != 0  ||  fread(&l, sizeof(sint32), 1, file) != 1  ) {
+		return "Malformed bmp file";
+	}
+	sint32 h = endian(l);
+
+	if(  fseek( file, 28, SEEK_SET ) != 0  ||  fread(&s, sizeof(sint16), 1, file) != 1  ) {
+		return "Malformed bmp file";
+	}
+	const sint16 bit_depth = endian(s);
+
+	if(  fseek( file, 30, SEEK_SET ) != 0  ||  fread(&l, sizeof(sint32), 1, file) != 1  ) {
+		return "Malformed bmp file";
+	}
+	const sint32 format = endian(l);
+
+	if(  fseek( file, 46, SEEK_SET ) != 0  ||  fread(&l, sizeof(sint32), 1, file) != 1  ) {
+		return "Malformed bmp file";
+	}
+	sint32 table = endian(l);
+
+	if(  (bit_depth!=8  &&  bit_depth!=24)  ||  format>1  ) {
+		return "Can only use 8 bit (RLE or normal) or 24 bit bitmaps!";
+	}
+
+	// skip parsing body
+	if(  update_only_values  ) {
+		ww = w;
+		hh = abs(h);
+		return NULL;
+	}
+
+	// now read the data and convert them on the fly
+	hfield = MALLOCN(sint8, w*h);
+
+	if (!hfield) {
+		return "Not enough memory";
+	}
+
+	memset( hfield, groundwater, w*h );
+
+	if(  bit_depth==8  ) {
+		// convert color tables to height levels
+		if(  table==0  ) {
+			table = 256;
+		}
+
+		sint8 h_table[256];
+		if(  fseek( file, 54, SEEK_SET ) != 0  ) {
+			return "Malformed bmp file";
+		}
+
+		for( int i=0;  i<table;  i++  ) {
+			const int B = fgetc(file);
+			const int G = fgetc(file);
+			const int R = fgetc(file);
+			const int A = fgetc(file); // dummy
+			if(  B==EOF  || G==EOF  || R==EOF  || A==EOF  ) {
+				return "Malformed bmp file";
 			}
-			// bitmap format
-			fseek( file, 10, SEEK_SET );
-			uint32 data_offset;
-			sint32 w, h, format, table;
-			sint16 bit_depth;
-#ifdef SIM_BIG_ENDIAN
-			uint32 l;
-			uint16 s;
-			fread( &l, 4, 1, file );
-			data_offset = endian(l);
-			fseek( file, 18, SEEK_SET );
-			fread( &l, 4, 1, file );
-			w = endian(l);
-			fread( &l, 4, 1, file );
-			h = endian(l);
-			fseek( file, 28, SEEK_SET );
-			fread( &s, 2, 1, file );
-			bit_depth = endian(s);
-			fread( &l, 4, 1, file );
-			format = endian(l);
-			fseek( file, 46, SEEK_SET );
-			fread( &l, 4, 1, file );
-			table = endian(l);
-#else
-			fread( &data_offset, 4, 1, file );
-			fseek( file, 18, SEEK_SET );
-			fread( &w, 4, 1, file );
-			fread( &h, 4, 1, file );
-			fseek( file, 28, SEEK_SET );
-			fread( &bit_depth, 2, 1, file );
-			fread( &format, 4, 1, file );
-			fseek( file, 46, SEEK_SET );
-			fread( &table, 4, 1, file );
-#endif
-			if((bit_depth!=8  &&  bit_depth!=24)  ||  format>1) {
-				if(!update_only_values) {
-					dbg->fatal("height_map_loader_t::get_height_data_from_file()","Can only use 8Bit (RLE or normal) or 24 bit bitmaps!");
+
+			h_table[i] = height_map_loader_t::rgb_to_height(R, G, B);
+		}
+
+		// now read the data
+		if(  fseek( file, data_offset, SEEK_SET ) != 0  ) {
+			return "Malformed bmp file";
+		}
+
+		if(  format==0  ) {
+			// uncompressed (usually mirrored, if h<0)
+			const bool mirror = (h<0);
+			h = abs(h);
+			for(  sint32 y=0;  y<h;  y++  ) {
+				const sint32 offset = mirror ? y*w : (h-y-1)*w;
+				for(  sint32 x=0;  x<w;  x++  ) {
+					const int res = fgetc(file);
+					if(  res==EOF  ) {
+						return "Malformed bmp file";
+					}
+					hfield[x+offset] = h_table[res];
 				}
-				fclose( file );
-				return false;
-			}
 
-			// skip parsing body
-			if(update_only_values) {
-				ww = w;
-				hh = abs(h);
-				return true;
+				// skip line offset
+				if(  w&1  ) {
+					if(  fgetc(file) == EOF  ) {
+						return "Malformed bmp file";
+					}
+				}
 			}
+		}
+		else {
+			// compressed RLE (reverse y, since mirrored)
+			sint32 x=0, y=h-1;
+			while(  !feof(file)  ) {
+				int res = fgetc(file);
+				if(  res == EOF  ) {
+					return "Malformed bmp file";
+				}
+				uint8 Count = res;
 
-			// now read the data and convert them on the fly
-			hfield = new sint8[w*h];
-			memset( hfield, groundwater, w*h );
-			if(bit_depth==8) {
-				// convert color tables to height levels
-				if(table==0) {
-					table = 256;
+				res = fgetc(file);
+				if(  res == EOF  ) {
+					return "Malformed bmp file";
 				}
-				sint8 h_table[256];
-				fseek( file, 54, SEEK_SET );
-				for( int i=0;  i<table;  i++  ) {
-					int B = fgetc(file);
-					int G = fgetc(file);
-					int R = fgetc(file);
-					fgetc(file); // dummy
-					h_table[i] = height_map_loader_t::rgb_to_height(R, G, B);
+
+				const uint8 ColorIndex = res;
+
+				if(  Count>0  ) {
+					for(  sint32 k=0;  k<Count;  k++, x++  ) {
+						hfield[x+(y*w)] = h_table[ColorIndex];
+					}
 				}
-				// now read the data
-				fseek( file, data_offset, SEEK_SET );
-				if(format==0) {
-					// uncompressed (usually mirrored, if h>0)
-					bool mirror = (h<0);
-					h = abs(h);
-					for(  sint32 y=0;  y<h;  y++  ) {
-						sint32 offset = mirror ? y*w : (h-y-1)*w;
-						for(  sint32 x=0;  x<w;  x++  ) {
-							hfield[x+offset] = h_table[fgetc(file)];
-						}
-						// skip line offset
-						if(w&1) {
-							fgetc(file);
+				else if(  Count==0  ) {
+					sint32 Flag = ColorIndex;
+					if(  Flag==0  ) {
+						// goto next line
+						x = 0;
+						y--;
+					}
+					else if(  Flag==1  ) {
+						// end of bitmap
+						break;
+					}
+					else if(  Flag==2  ) {
+						// skip with cursor
+						const int xx = fgetc(file);
+						const int yy = fgetc(file);
+
+						if(  xx==EOF  || yy==EOF  ) {
+							return "Malformed bmp file";
 						}
+
+						x += (uint8)xx;
+						y -= (uint8)yy;
 					}
-				}
-				else {
-					// compressed RLE (reverse y, since mirrored)
-					sint32 x=0, y=h-1;
-					while (!feof(file)) {
-						uint8 Count= fgetc(file);
-						uint8 ColorIndex = fgetc(file);
-
-						if (Count > 0) {
-							for( sint32 k = 0;  k < Count;  k++, x++  ) {
-								hfield[x+(y*w)] = h_table[ColorIndex];
-							}
-						} else if (Count == 0) {
-							sint32 Flag = ColorIndex;
-							if (Flag == 0) {
-								// goto next line
-								x = 0;
-								y--;
-							}
-							else if (Flag == 1) {
-								// end of bitmap
-								break;
-							}
-							else if (Flag == 2) {
-								// skip with cursor
-								x += (uint8)fgetc(file);
-								y -= (uint8)fgetc(file);
-							}
-							else {
-								// uncompressed run
-								Count = Flag;
-								for( sint32 k = 0;  k < Count;  k++, x++  ) {
-									hfield[x+y*w] = h_table[(uint8)fgetc(file)];
-								}
-								if (ftell(file) & 1) { // always even offset in file
-									fseek(file, 1, SEEK_CUR);
-								}
+					else {
+						// uncompressed run
+						Count = Flag;
+						for(  sint32 k=0;  k<Count;  k++, x++  ) {
+							const int idx = fgetc(file);
+							if(  idx==EOF  ) {
+								return "Malformed bmp file";
 							}
+
+							hfield[x+y*w] = h_table[(uint8)idx];
+						}
+
+						// always even offset in file
+						const long int pos = ftell(file);
+						if(  pos==-1L  ||  (pos&1  &&  fseek(file, 1, SEEK_CUR)!=0)  ) {
+							return "Malformed bmp file";
 						}
 					}
 				}
 			}
-			else {
-				// uncompressed 24 bits
-				bool mirror = (h<0);
-				h = abs(h);
-				for(  sint32 y=0;  y<h;  y++  ) {
-					sint32 offset = mirror ? y*w : (h-y-1)*w;
-					for(  sint32 x=0;  x<w;  x++  ) {
-						int B = fgetc(file);
-						int G = fgetc(file);
-						int R = fgetc(file);
-						hfield[x+offset] = height_map_loader_t::rgb_to_height(R, G, B);
-					}
-					fseek( file, (4-((w*3)&3))&3, SEEK_CUR ); // skip superfluos bytes at the end of each scanline
-				}
-			}
-			// success ...
-			fclose(file);
-			ww = w;
-			hh = h;
-			return true;
 		}
-		else {
-			// ppm format
-			char buf[255];
-			char *c = id+2;
-			sint32 param[3]={0,0,0};
-			for(int index=0;  index<3;  ) {
-				// the format is "P6[whitespace]width[whitespace]height[[whitespace bitdepth]]newline]
-				// however, Photoshop is the first program, that uses space for the first whitespace ...
-				// so we cater for Photoshop too
-				while(*c  &&  *c<=32) {
-					c++;
-				}
-				// usually, after P6 there comes a comment with the maker
-				// but comments can be anywhere
-				if(*c==0) {
-					read_line(buf, sizeof(buf), file);
-					c = buf;
-					continue;
-				}
-				param[index++] = atoi(c);
-				while(*c>='0'  &&  *c<='9') {
-					c++;
+	}
+	else {
+		// uncompressed 24 bits
+		const bool mirror = (h<0);
+		h = abs(h);
+
+		for(  sint32 y=0;  y<h;  y++  ) {
+			const sint32 offset = mirror ? y*w : (h-y-1)*w;
+			for(  sint32 x=0;  x<w;  x++  ) {
+				const int B = fgetc(file);
+				const int G = fgetc(file);
+				const int R = fgetc(file);
+
+				if(  B==EOF  ||  G==EOF  ||  R==EOF  ) {
+					return "Malformed bmp file";
 				}
+
+				hfield[x+offset] = height_map_loader_t::rgb_to_height(R, G, B);
 			}
-			// now the data
-			sint32 w = param[0];
-			sint32 h = param[1];
-			if(param[2]!=255) {
-				fclose(file);
-				if(!update_only_values) {
-					dbg->fatal("height_map_loader_t::load_heightfield()","Heightfield has wrong color depth %d", param[2] );
-				}
-				return false;
+
+			// skip superfluous bytes at the end of each scanline
+			if(  fseek( file, (4-((w*3)&3))&3, SEEK_CUR ) != 0  ) {
+				return "Malformed bmp file";
 			}
+		}
+	}
+
+	ww = w;
+	hh = h;
+	return NULL;
+}
+
+
+const char *height_map_loader_t::read_ppm( FILE *file, sint8 groundwater, sint8 *&hfield, sint16 &ww, sint16 &hh, bool update_only_values )
+{
+	// ppm format
+	char buf[255];
+	const char *c = "";
+	sint32 param[3] = {0, 0, 0};
+
+	for(  int index=0;  index<3;  ) {
+		// the format is "P6[whitespace]width[whitespace]height[[whitespace bitdepth]]newline]
+		// however, Photoshop is the first program that uses space for the first whitespace
+		// so we cater for Photoshop too
+		while(  *c!=0  &&  *c<=32  ) {
+			c++;
+		}
 
-			// report only values
-			if(update_only_values) {
-				fclose(file);
-				ww = w;
-				hh = h;
-				return true;
+		// usually, after P6 there comes a comment with the maker
+		// but comments can be anywhere
+		if(  *c==0  ) {
+			if(  read_line(buf, sizeof(buf), file) == NULL  ) {
+				return "Malformed ppm file";
 			}
 
-			// ok, now read them in
-			hfield = new sint8[w*h];
-			memset( hfield, groundwater, w*h );
+			c = buf;
+			continue;
+		}
 
-			for(sint16 y=0; y<h; y++) {
-				for(sint16 x=0; x<w; x++) {
-					int R = fgetc(file);
-					int G = fgetc(file);
-					int B = fgetc(file);
-					hfield[x+(y*w)] = height_map_loader_t::rgb_to_height(R, G, B);
-				}
+		param[index++] = atoi(c);
+		while(  *c>='0'  &&  *c<='9'  ) {
+			c++;
+		}
+	}
+
+	// now the data
+	const sint32 w = param[0];
+	const sint32 h = param[1];
+
+	if(  param[2]!=255  ) {
+		return "Heightfield has wrong color depth (must be 255)";
+	}
+
+	// report only values
+	if(  update_only_values  ) {
+		ww = w;
+		hh = h;
+		return NULL;
+	}
+
+	// ok, now read them in
+	hfield = MALLOCN(sint8, w*h);
+
+	if (!hfield) {
+		return "Not enough memory";
+	}
+
+	memset( hfield, groundwater, w*h );
+
+	for(  sint16 y=0;  y<h;  y++  ) {
+		for(  sint16 x=0;  x<w;  x++  ) {
+			const int R = fgetc(file);
+			const int G = fgetc(file);
+			const int B = fgetc(file);
+
+			if(  R==EOF  ||  G==EOF  || B==EOF  ) {
+				return "Malformed ppm file";
 			}
 
-			// success ...
-			fclose(file);
-			ww = w;
-			hh = h;
-			return true;
+			hfield[x+(y*w)] = height_map_loader_t::rgb_to_height(R, G, B);
 		}
 	}
-	return false;
+
+	ww = w;
+	hh = h;
+	return NULL;
+}
+
+
+sint8 height_map_loader_t::rgb_to_height(const int r, const int g, const int b)
+{
+	const sint32 h0 = (2*r + 3*g + b); // 0..0x5FA
+
+	switch (conv_mode) {
+	case env_t::height_conversion_mode::legacy_small: {
+		// old style
+		if(  env_t::pak_height_conversion_factor == 2  ) {
+			return ::clamp(h0/32 - 28, min_allowed_height, max_allowed_height); // -28..19
+		}
+		else {
+			return ::clamp(h0/64 - 14, min_allowed_height, max_allowed_height); // -14..9
+		}
+	}
+	case env_t::height_conversion_mode::legacy_large: {
+		// new style, heights more spread out
+		if(  env_t::pak_height_conversion_factor == 2  ) {
+			return ::clamp(h0/24 - 34, min_allowed_height, max_allowed_height); // -34..29
+		}
+		else {
+			return ::clamp(h0/48 - 18, min_allowed_height, max_allowed_height); // -18..13
+		}
+	}
+	case env_t::height_conversion_mode::linear: {
+		return min_allowed_height + (h0*(max_allowed_height-min_allowed_height)) / 0x5FA;
+	}
+	case env_t::height_conversion_mode::clamp: {
+		return ::clamp(((h0 * 0xFF) / 0x5FA) - 128, min_allowed_height, max_allowed_height);
+	}
+	default:
+		dbg->fatal("height_map_loader_t::rgb_to_height", "Unhandled height conversion mode %d", conv_mode);
+	}
+
+	return 0;
 }
diff --git dataobj/height_map_loader.h dataobj/height_map_loader.h
index 4c4640e878..00c2539958 100644
--- dataobj/height_map_loader.h
+++ dataobj/height_map_loader.h
@@ -10,43 +10,39 @@
 #include "../simtypes.h"
 #include "environment.h"
 
-/* code for loading heightmaps */
-class height_map_loader_t {
+
+/**
+ * Loads height data from BMP or PPM files.
+ */
+class height_map_loader_t
+{
 public:
-	height_map_loader_t(bool height_map_conversion_version);
+	height_map_loader_t(sint8 min_allowed_height, sint8 max_allowed_height, env_t::height_conversion_mode conv_mode);
 
 	/**
-	 * Reads height data from 8 or 25 bit bmp or ppm files.
-	 * @return Either pointer to heightfield (use delete [] for it) or NULL.
+	 * Reads height data from 8 or 24 bit bmp or ppm files.
+	 *
+	 * @param filename the file to load the height data from.
+	 * @param[out] hfield 2d array of height values.
+	 * @param[out] ww,hh width and height of @p hfield. On failure, these values are undefined.
+	 * @param update_only_values When true, do not allocate the height field; instead, only update @p ww and @p hh
+	 *
+	 * @return true on success, false on failure. On success, @p hfield contains
+	 * the height field data (must be free()'d by the caller unless @p update_only_values is set).
+	 * On failure, @p hfield is set to NULL (Does not need to be free()'d)
 	 */
 	bool get_height_data_from_file( const char *filename, sint8 groundwater, sint8 *&hfield, sint16 &ww, sint16 &hh, bool update_only_values );
 
 private:
-	inline sint8 rgb_to_height( const int r, const int g, const int b ) {
-		const sint16 h0 = (r*2+g*3+b);
-		if(  !height_map_conversion_version_new  ) {
-			// old style
-			if(  env_t::pak_height_conversion_factor == 2  ) {
-				// was: return (((r*2+g*3+b)/4 - 224) & 0xFFF8)/8;
-				return h0/32 - 28;
-			}
-			else {
-				// was: return (( ((r*2+g*3+b)/4 - 224)) & 0xFFF0)/16;
-				return h0/64 - 14;
-			}
-		}
-		else {
-			// new style, heights more spread out
-			if(  env_t::pak_height_conversion_factor == 2  ) {
-				return h0/24 - 34;
-			}
-			else {
-				return h0/48 - 18;
-			}
-		}
-	}
-
-	const bool height_map_conversion_version_new;
+	sint8 rgb_to_height( const int r, const int g, const int b );
+
+	const char *read_bmp(FILE *file, sint8 groundwater, sint8 *&hfield, sint16 &ww, sint16 &hh, bool update_only_values);
+	const char *read_ppm(FILE *file, sint8 groundwater, sint8 *&hfield, sint16 &ww, sint16 &hh, bool update_only_values);
+
+private:
+	const sint8 min_allowed_height;
+	const sint8 max_allowed_height;
+	const env_t::height_conversion_mode conv_mode;
 };
 
 #endif
diff --git dataobj/settings.cc dataobj/settings.cc
index 307d2ad019..eb7ac6b559 100644
--- dataobj/settings.cc
+++ dataobj/settings.cc
@@ -1319,7 +1319,8 @@ void settings_t::parse_simuconf(tabfile_t& simuconf, sint16& disp_width, sint16&
 	starting_year = contents.get_int("starting_year", starting_year );
 	starting_month = contents.get_int("starting_month", starting_month+1)-1;
 
-	env_t::new_height_map_conversion = contents.get_int("new_height_map_conversion", env_t::new_height_map_conversion );
+	env_t::height_conv_mode = (env_t::height_conversion_mode)::clamp(contents.get_int("new_height_map_conversion", (int)env_t::height_conv_mode ), 0, env_t::height_conversion_mode::MAX_MODES);
+
 	river_number = contents.get_int("river_number", river_number );
 	min_river_length = contents.get_int("river_min_length", min_river_length );
 	max_river_length = contents.get_int("river_max_length", max_river_length );
@@ -1484,13 +1485,10 @@ void settings_t::parse_simuconf(tabfile_t& simuconf, sint16& disp_width, sint16&
 	max_rail_convoi_length = contents.get_int("max_rail_convoi_length",max_rail_convoi_length);
 	max_road_convoi_length = contents.get_int("max_road_convoi_length",max_road_convoi_length);
 	max_ship_convoi_length = contents.get_int("max_ship_convoi_length",max_ship_convoi_length);
-	max_air_convoi_length = contents.get_int("max_air_convoi_length",max_air_convoi_length);
+	max_air_convoi_length  = contents.get_int("max_air_convoi_length",max_air_convoi_length);
 
-	world_maximum_height = contents.get_int("world_maximum_height",world_maximum_height);
-	world_minimum_height = contents.get_int("world_minimum_height",world_minimum_height);
-	if(  world_minimum_height>=world_maximum_height  ) {
-		world_minimum_height = world_maximum_height-1;
-	}
+	world_maximum_height = clamp(contents.get_int("world_maximum_height",world_maximum_height), 16, 127);
+	world_minimum_height = clamp(contents.get_int("world_minimum_height",world_minimum_height), -127, -12);
 
 	// Default pak file path
 	objfilename = ltrim(contents.get_string("pak_file_path", "" ) );
diff --git gui/load_relief_frame.cc gui/load_relief_frame.cc
index 5dd7618846..9a1901efaf 100644
--- gui/load_relief_frame.cc
+++ gui/load_relief_frame.cc
@@ -14,6 +14,32 @@
 #include "../dataobj/settings.h"
 #include "../dataobj/environment.h"
 #include "../dataobj/height_map_loader.h"
+#include "components/gui_scrolled_list.h"
+
+
+static const char *load_mode_texts[env_t::MAX_MODES] =
+{
+	"legacy (small heights)",
+	"legacy (large heights)",
+	"linear",
+	"clamp"
+};
+
+
+class load_relief_mode_scrollitem_t : public gui_scrolled_list_t::const_text_scrollitem_t
+{
+public:
+	load_relief_mode_scrollitem_t(env_t::height_conversion_mode mode) :
+		gui_scrolled_list_t::const_text_scrollitem_t(translator::translate(load_mode_texts[(int)mode]), SYSCOL_TEXT),
+		mode(mode)
+	{}
+
+	env_t::height_conversion_mode get_mode() const { return mode; }
+
+private:
+	env_t::height_conversion_mode mode;
+};
+
 
 /**
  * Action, started on button pressing
@@ -23,17 +49,33 @@ bool load_relief_frame_t::item_action(const char *fullpath)
 	sets->heightfield = fullpath;
 
 	if (gui_frame_t *new_world_gui = win_get_magic( magic_welt_gui_t )) {
+		const gui_scrolled_list_t::scrollitem_t *selected = load_mode.get_selected_item();
+		if (selected) {
+			env_t::height_conv_mode = static_cast<const load_relief_mode_scrollitem_t *>(selected)->get_mode();
+		}
+
 		static_cast<welt_gui_t*>(new_world_gui)->update_preview(true);
 	}
+
 	return false;
 }
 
 
 load_relief_frame_t::load_relief_frame_t(settings_t* const sets) : savegame_frame_t( NULL, false, "maps/", env_t::show_delete_buttons )
 {
-	new_format.init( button_t::square_automatic, "Maximize height levels");
-	new_format.pressed = env_t::new_height_map_conversion;
-	bottom_left_frame.add_component( &new_format );
+	gui_aligned_container_t *table = bottom_left_frame.add_table(2, 1);
+		load_mode_label.init(translator::translate("Load mode:"), scr_coord(0, 0));
+		load_mode_label.set_visible(true);
+		table->add_component( &load_mode_label );
+
+		load_mode.init(scr_coord(0, 0));
+		load_mode.new_component<load_relief_mode_scrollitem_t>(env_t::height_conversion_mode::legacy_small);
+		load_mode.new_component<load_relief_mode_scrollitem_t>(env_t::height_conversion_mode::legacy_large);
+		load_mode.new_component<load_relief_mode_scrollitem_t>(env_t::height_conversion_mode::linear);
+		load_mode.new_component<load_relief_mode_scrollitem_t>(env_t::height_conversion_mode::clamp);
+		load_mode.set_selection(env_t::height_conversion_mode::linear);
+		table->add_component( &load_mode );
+	bottom_left_frame.end_table();
 
 	const std::string extra_path = env_t::program_dir + env_t::objfilename + "maps/";
 	this->add_path(extra_path.c_str());
@@ -49,27 +91,48 @@ const char *load_relief_frame_t::get_info(const char *fullpath)
 	static char size[64];
 
 	sint16 w, h;
-	sint8 *h_field ;
-	height_map_loader_t hml(new_format.pressed);
+	sint8 *h_field = NULL;
+	const sint8 min_h = world()->get_settings().get_minimumheight();
+	const sint8 max_h = world()->get_settings().get_maximumheight();
+
+	const gui_scrolled_list_t::scrollitem_t *selected = load_mode.get_selected_item();
+	env_t::height_conversion_mode new_mode = env_t::height_conv_mode;
 
+	if (selected) {
+		new_mode = static_cast<const load_relief_mode_scrollitem_t *>(selected)->get_mode();
+	}
+
+	height_map_loader_t hml(min_h, max_h, env_t::height_conv_mode);
 	if(hml.get_height_data_from_file(fullpath, (sint8)sets->get_groundwater(), h_field, w, h, true )) {
 		sprintf( size, "%i x %i", w, h );
-		env_t::new_height_map_conversion = new_format.pressed;
+		env_t::height_conv_mode = new_mode;
 		return size;
 	}
+
 	return "";
 }
 
 
 bool load_relief_frame_t::check_file( const char *fullpath, const char * )
 {
+	const sint8 min_h = world()->get_settings().get_minimumheight();
+	const sint8 max_h = world()->get_settings().get_maximumheight();
+
+	const gui_scrolled_list_t::scrollitem_t *selected = load_mode.get_selected_item();
+	env_t::height_conversion_mode new_mode = env_t::height_conv_mode;
+
+	if (selected) {
+		new_mode = static_cast<const load_relief_mode_scrollitem_t *>(selected)->get_mode();
+	}
+
+	height_map_loader_t hml(min_h, max_h, env_t::height_conv_mode);
 	sint16 w, h;
-	sint8 *h_field;
+	sint8 *h_field = NULL;
 
-	height_map_loader_t hml(new_format.pressed);
 	if(hml.get_height_data_from_file(fullpath, (sint8)sets->get_groundwater(), h_field, w, h, true )) {
+		env_t::height_conv_mode = new_mode;
 		return w>0  &&  h>0;
-		env_t::new_height_map_conversion = new_format.pressed;
 	}
+
 	return false;
 }
diff --git gui/load_relief_frame.h gui/load_relief_frame.h
index 971df2c0cc..79b79d93b8 100644
--- gui/load_relief_frame.h
+++ gui/load_relief_frame.h
@@ -7,17 +7,20 @@
 #define GUI_LOAD_RELIEF_FRAME_H
 
 
+#include "components/gui_combobox.h"
 #include "savegame_frame.h"
 
 
 class settings_t;
 
+
 class load_relief_frame_t : public savegame_frame_t
 {
 private:
 	settings_t* sets;
 
-	button_t new_format;
+	gui_label_t load_mode_label;
+	gui_combobox_t load_mode;
 
 protected:
 	bool item_action(const char *fullpath) OVERRIDE;
diff --git gui/loadfont_frame.cc gui/loadfont_frame.cc
index 6f06878ade..4a4be1ba2e 100644
--- gui/loadfont_frame.cc
+++ gui/loadfont_frame.cc
@@ -253,7 +253,6 @@ void loadfont_frame_t::rdwr( loadsave_t *file )
 }
 
 
-
 bool loadfont_frame_t::action_triggered(gui_action_creator_t *component, value_t v)
 {
 	if(  &unicode_only==component  ) {
diff --git gui/welt.cc gui/welt.cc
index b76f161b4b..ff307442e3 100644
--- gui/welt.cc
+++ gui/welt.cc
@@ -274,9 +274,13 @@ bool welt_gui_t::update_from_heightfield(const char *filename)
 {
 	DBG_MESSAGE("welt_gui_t::update_from_heightfield()", "%s", filename);
 
+	const sint8 min_h = env_t::default_settings.get_minimumheight();
+	const sint8 max_h = env_t::default_settings.get_maximumheight();
+
+	height_map_loader_t hml(min_h, max_h, env_t::height_conv_mode);
 	sint16 w, h;
 	sint8 *h_field=NULL;
-	height_map_loader_t hml(sets);
+
 	if(hml.get_height_data_from_file(filename, (sint8)sets->get_groundwater(), h_field, w, h, false )) {
 		sets->set_size_x(w);
 		sets->set_size_y(h);
@@ -295,8 +299,10 @@ bool welt_gui_t::update_from_heightfield(const char *filename)
 			}
 		}
 		map_preview.set_map_data(&map);
+		free(h_field);
 		return true;
 	}
+
 	return false;
 }
 
diff --git simworld.cc simworld.cc
index bf8213cbe5..c06df69d9b 100644
--- simworld.cc
+++ simworld.cc
@@ -6274,13 +6274,17 @@ uint8 karte_t::sp2num(player_t *player)
 void karte_t::load_heightfield(settings_t* const sets)
 {
 	sint16 w, h;
-	sint8 *h_field;
-	height_map_loader_t hml(sets);
+	sint8 *h_field = NULL;
+	const sint8 min_h = sets->get_minimumheight();
+	const sint8 max_h = sets->get_maximumheight();
+
+	height_map_loader_t hml(min_h, max_h, env_t::height_conv_mode);
+
 	if(hml.get_height_data_from_file(sets->heightfield.c_str(), (sint8)(sets->get_groundwater()), h_field, w, h, false )) {
 		sets->set_size(w,h);
 		// create map
 		init(sets,h_field);
-		delete [] h_field;
+		free(h_field);
 	}
 	else {
 		dbg->error("karte_t::load_heightfield()","Cant open file '%s'", sets->heightfield.c_str());