diff --git a/OpenRA.Mods.Common/MapGenerator/Terraformer.cs b/OpenRA.Mods.Common/MapGenerator/Terraformer.cs
index 67068c009a..75ca8e2ffe 100644
--- a/OpenRA.Mods.Common/MapGenerator/Terraformer.cs
+++ b/OpenRA.Mods.Common/MapGenerator/Terraformer.cs
@@ -176,7 +176,7 @@ namespace OpenRA.Mods.Common.MapGenerator
 		{
 			var maxTerrainHeight = Map.Grid.MaximumTerrainHeight;
 			var tl = new PPos(1, 1 + maxTerrainHeight);
-			var br = new PPos(Map.MapSize.Width - 2, Map.MapSize.Height + maxTerrainHeight - 2);
+			var br = new PPos(Map.MapSize.Width - 2, Map.MapSize.Height - maxTerrainHeight - 2);
 			Map.SetBounds(tl, br);
 			Map.Title = MapGenerationArgs.Title;
 			Map.Author = MapGenerationArgs.Author;
@@ -185,12 +185,26 @@ namespace OpenRA.Mods.Common.MapGenerator
 
 		/// <summary>
 		/// Commits draft data to the map, such as player and actor definitions.
+		/// This may trigger some initialization of map data structures that could become invalid
+		/// if further edits to the map are made.
 		/// </summary>
 		public void BakeMap()
 		{
 			var playerCount = ActorsOfType("mpspawn").Count();
 			Map.PlayerDefinitions = new MapPlayers(Map.Rules, playerCount).ToMiniYaml();
+
+			// Return true iff any of the actors projected footprint satisfies Map.Contains(PPos).
+			// Note that this is not the same as Map.Tiles.Contains or Map.Bounds.Contains.
+			// Note that calling this initializes cell projections.
+			bool HasProjectedFootprintInMap(ActorPlan plan)
+			{
+				return plan.Footprint()
+					.SelectMany(f => Map.ProjectedCellsCovering(f.Key.ToMPos(Map)))
+					.Any(Map.Contains);
+			}
+
 			Map.ActorDefinitions = ActorPlans
+				.Where(HasProjectedFootprintInMap)
 				.Select((plan, i) => new MiniYamlNode($"Actor{i}", plan.Reference.Save()))
 				.ToImmutableArray();
 		}
@@ -261,10 +275,13 @@ namespace OpenRA.Mods.Common.MapGenerator
 					zoneable[mpos] = value;
 		}
 
+		/// <summary>
+		/// Zone based on Map.Bounds.Contains. This is stricter than Map.Contains, ignoring height.
+		/// </summary>
 		public void ZoneFromOutOfBounds<T>(CellLayer<T> zoneable, T value)
 		{
 			foreach (var mpos in Map.AllCells.MapCoords)
-				if (!Map.Contains(mpos))
+				if (!Map.Bounds.Contains(mpos.U, mpos.V))
 					zoneable[mpos] = value;
 		}
 
@@ -1687,10 +1704,10 @@ namespace OpenRA.Mods.Common.MapGenerator
 				throw new ArgumentException("fillSide was not In or Out");
 
 			var notFillSide = fillSide == Side.In ? Side.Out : Side.In;
-			var fillSeeds = CellLayerUtils.Create(Map, (MPos mpos) =>
+			var fillSeeds = CellLayerUtils.Create(Map, mpos =>
 				sides[mpos] == fillSide &&
 				!mask[mpos] &&
-				Map.Contains(mpos));
+				Map.Bounds.Contains(mpos.U, mpos.V));
 			fillSeeds = ImproveSymmetry(fillSeeds, false, (a, b) => a || b);
 			var fillable = CellLayerUtils.Map(sides, side => side != notFillSide);
 			CellLayerUtils.SimpleFloodFill(
diff --git a/OpenRA.Mods.Common/Traits/World/ExperimentalMapGenerator.cs b/OpenRA.Mods.Common/Traits/World/ExperimentalMapGenerator.cs
index 740766a9e1..437a1d5a58 100644
--- a/OpenRA.Mods.Common/Traits/World/ExperimentalMapGenerator.cs
+++ b/OpenRA.Mods.Common/Traits/World/ExperimentalMapGenerator.cs
@@ -747,7 +747,7 @@ namespace OpenRA.Mods.Common.Traits
 
 					var replace = PlayableToReplaceable();
 					foreach (var mpos in map.AllCells.MapCoords)
-						if (playable[mpos] || !map.Contains(mpos))
+						if (playable[mpos] || !map.Bounds.Contains(mpos.U, mpos.V))
 							replace[mpos] = MultiBrush.Replaceability.None;
 
 					terraformer.PaintArea(debrisTilingRandom, replace, param.UnplayableObstacles);
diff --git a/OpenRA.Mods.Common/Widgets/Logic/Editor/MapGeneratorToolLogic.cs b/OpenRA.Mods.Common/Widgets/Logic/Editor/MapGeneratorToolLogic.cs
index 1497c84817..211b745208 100644
--- a/OpenRA.Mods.Common/Widgets/Logic/Editor/MapGeneratorToolLogic.cs
+++ b/OpenRA.Mods.Common/Widgets/Logic/Editor/MapGeneratorToolLogic.cs
@@ -261,8 +261,7 @@ namespace OpenRA.Mods.Common.Widgets.Logic
 		{
 			var map = world.Map;
 			var terrainInfo = modData.DefaultTerrainInfo[map.Tileset];
-			var size = new Size(map.Bounds.Width + 2, map.Bounds.Height + 2);
-			var args = settings.Compile(terrainInfo, size);
+			var args = settings.Compile(terrainInfo, map.MapSize);
 
 			// Run main generator logic. May throw.
 			var generateStopwatch = Stopwatch.StartNew();
@@ -301,12 +300,15 @@ namespace OpenRA.Mods.Common.Widgets.Logic
 				previews.Add(kv.Key, preview);
 			}
 
-			var offset = map.CellContaining(map.ProjectedTopLeft) - generatedMap.CellContaining(generatedMap.ProjectedTopLeft);
-			var blitSource = new EditorBlitSource(generatedMap.AllCells, previews, tiles);
+			var cellBounds = CellLayerUtils.CellBounds(map);
+			var topLeft = new CPos(cellBounds.TopLeft.X, cellBounds.TopLeft.Y);
+			var bottomRight = new CPos(cellBounds.BottomRight.X, cellBounds.BottomRight.Y);
+			var cellRegion = new CellRegion(map.Grid.Type, topLeft, bottomRight);
+			var blitSource = new EditorBlitSource(cellRegion, previews, tiles);
 			var editorBlit = new EditorBlit(
 				MapBlitFilters.All,
 				resourceLayer,
-				new CPos(offset.X, offset.Y),
+				topLeft,
 				map,
 				blitSource,
 				editorActorLayer,
diff --git a/OpenRA.Mods.Common/Widgets/Logic/MapGeneratorLogic.cs b/OpenRA.Mods.Common/Widgets/Logic/MapGeneratorLogic.cs
index 3622081bf9..9fb859bd4f 100644
--- a/OpenRA.Mods.Common/Widgets/Logic/MapGeneratorLogic.cs
+++ b/OpenRA.Mods.Common/Widgets/Logic/MapGeneratorLogic.cs
@@ -234,9 +234,15 @@ namespace OpenRA.Mods.Common.Widgets.Logic
 
 		void RandomizeSize()
 		{
+			var mapGrid = modData.Manifest.Get<MapGrid>();
 			var sizeRange = MapSizes[selectedSize];
 			var width = Game.CosmeticRandom.Next(sizeRange.X, sizeRange.Y);
-			size = new Size(width + 2, width + 2);
+			var height =
+				mapGrid.Type == MapGridType.RectangularIsometric
+					? width * 2
+					: width;
+
+			size = new Size(width + 2, height + mapGrid.MaximumTerrainHeight * 2 + 2);
 		}
 
 		void RefreshSettings()