dem-with-water-bodies now checks whether the HGT file already exists

breki · Aug 8, 2024 · 6951688 · 6951688
1 parent 9c7fee9
commit 6951688
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Showing 6 changed files with 81 additions and 67 deletions.
diff --git a/Demeton.Tests/Dem/Reading HGT files.fs b/Demeton.Tests/Dem/Reading HGT files.fs
@@ -36,7 +36,7 @@ let ``Can read SRTM heights`` () =
                1uy |]
         )
 
-    let heights = Hgt.readFromStream 2 stream
+    let heights = Hgt.readHeightsFromStream 2 stream
 
     heights |> should equal [| 2560s; 0s; 2561s; 1s |]
 
@@ -45,7 +45,7 @@ let ``Can read null SRTM heights`` () =
     use stream =
         new MemoryStream([| 0x80uy; 0uy; 10uy; 0uy; 10uy; 0uy; 0uy; 0uy |])
 
-    let heights = Hgt.readFromStream 1 stream
+    let heights = Hgt.readHeightsFromStream 1 stream
 
     heights |> should equal [| DemHeightNone |]
 
@@ -56,7 +56,7 @@ let ``Can handle negative SRTM heights`` () =
             [| 255uy; 0b10011100uy; 10uy; 0uy; 10uy; 0uy; 0uy; 0uy |]
         )
 
-    let heights = Hgt.readFromStream 1 stream
+    let heights = Hgt.readHeightsFromStream 1 stream
 
     heights |> should equal [| -100s |]
 
@@ -98,7 +98,7 @@ let ``Can create heights array from SRTM heights sequence`` () =
 
     use stream = new MemoryStream(byteArray)
 
-    let tile = Hgt.createDemTileFromStream tileSize (demTileId 0 16 45) stream
+    let tile = Hgt.readHeightsArrayFromStream tileSize (demTileId 0 16 45) stream
 
     test <@ tile.Width = tileSize @>
     test <@ tile.Height = tileSize @>
@@ -117,6 +117,6 @@ let ``Can read HGT file`` () =
 
     test <@ stream <> null @>
 
-    let heights = Hgt.createDemTileFromStream 3600 tileId stream
+    let heights = Hgt.readHeightsArrayFromStream 3600 tileId stream
     test <@ heights.Width = 3600 @>
     test <@ heights.Height = 3600 @>
diff --git a/Demeton.Tests/Png/IDAT compression.fs b/Demeton.Tests/Png/IDAT compression.fs
@@ -51,7 +51,7 @@ let ``Determining the compression rate`` () =
 
     printfn "Reading the heights array..."
 
-    let heightsArray = Hgt.createDemTileFromStream 3600 tileId hgtStream
+    let heightsArray = Hgt.readHeightsArrayFromStream 3600 tileId hgtStream
 
     printfn
         "%d Encoding heights into a raw image data..."

diff --git a/Demeton.Tests/Srtm/Converting HGT to PNG.fs b/Demeton.Tests/Srtm/Converting HGT to PNG.fs
@@ -86,7 +86,7 @@ let ``Can convert a HGT file into PNG image`` () =
 
     printfn "Reading the heights array..."
 
-    let heightsArray = Hgt.createDemTileFromStream 3600 tileId hgtStream
+    let heightsArray = Hgt.readHeightsArrayFromStream 3600 tileId hgtStream
 
     printfn "%d Encoding heights into the PNG..." clock.ElapsedMilliseconds
 

diff --git a/Demeton/Commands/DemWithWaterBodiesCommand.fs b/Demeton/Commands/DemWithWaterBodiesCommand.fs
@@ -21,7 +21,7 @@ open Raster
 type Options =
     { TileId: DemTileId
       HgtSize: int
-      LocalCacheDir: string}
+      LocalCacheDir: string }
 
 [<Literal>]
 let TileIdParameter = "tile-id"
@@ -219,63 +219,77 @@ let extendHeightsArrayWithAdditionalRowAndColumn (heightsArray: HeightsArray) =
         HeightsArrayDirectImport extendedCells
     )
 
-// todo 3: if the HGT already exists, just read it
-
 let ensureHgtFile cacheDir hgtSize tileId : HeightsArray option =
-    fetchAw3dTile tileId cacheDir
-    |> Result.map (fun aw3dTile ->
-        let availableWorldCoverTiles =
-            ensureGeoJsonFile cacheDir FileSys.fileExists FileSys.downloadFile
-            |> listAllAvailableFiles FileSys.openFileToRead
-            |> Set.ofSeq
-
-        let downsampledAw3dTile = aw3dTile |> downsampleAw3dTile hgtSize
-
-        loadWaterBodiesTileFromCache cacheDir availableWorldCoverTiles tileId
-        |> makeNoneFileIfNeeded cacheDir
-        |> extractWaterBodiesTileFromWorldCoverTileIfNeeded cacheDir
-        |> function
-            | CachedTileLoaded tileHeightsArray ->
-                // todo 20: simplify water bodies
-
-                tileHeightsArray
-                |> Option.map (fun tileHeightsArray ->
-                    let downsampledWaterBodiesTile =
-                        tileHeightsArray
-                        |> downsampleWaterBodiesHeightsArray hgtSize
-
-                    let demWaterBodiesTile =
-                        downsampledAw3dTile
-                        |> encodeWaterBodiesInfoIntoDem
-                            downsampledWaterBodiesTile
-                        // extend the heights array with one additional
-                        //  row and column so it is compatible with the original
-                        //  SRTM HGT files
-                        |> extendHeightsArrayWithAdditionalRowAndColumn
-
-                    demWaterBodiesTile
-                    |> Hgt.writeHeightsArrayToFile (
-                        Path.Combine
-                            (cacheDir,
-                             "AW3D-WaterBodies",
-                             hgtSize.ToString(),
-                             toTileName tileId + ".hgt"))
-                    |> ignore
-
-                    demWaterBodiesTile
-                )
-            | TileNeedsToBeDownloaded _ ->
-                invalidOp "Bug: this should never happen"
-            | TileDoesNotExistInWorldCover _ ->
-                NotImplementedException(
-                    "The case when there is no WorldCover tile"
-                )
-                |> raise
+    let hgtFileName =
+        Path.Combine(
+            cacheDir,
+            "AW3D-WaterBodies",
+            hgtSize.ToString(),
+            toTileName tileId + ".hgt"
         )
-    |> function
-    | Ok heightsArray -> heightsArray
-    | Error errorMessage ->
-        invalidOp errorMessage
+
+    if FileSys.fileExists hgtFileName then
+        Log.info "The HGT file already exists at '%s'." hgtFileName
+
+        FileSys.openFileToRead hgtFileName
+        |> function
+            | Ok stream ->
+                use stream = stream
+                Some(Hgt.readHeightsArrayFromStream hgtSize tileId stream)
+            | Error error -> raise error.Exception
+    else
+        fetchAw3dTile tileId cacheDir
+        |> Result.map (fun aw3dTile ->
+            let availableWorldCoverTiles =
+                ensureGeoJsonFile
+                    cacheDir
+                    FileSys.fileExists
+                    FileSys.downloadFile
+                |> listAllAvailableFiles FileSys.openFileToRead
+                |> Set.ofSeq
+
+            let downsampledAw3dTile = aw3dTile |> downsampleAw3dTile hgtSize
+
+            loadWaterBodiesTileFromCache
+                cacheDir
+                availableWorldCoverTiles
+                tileId
+            |> makeNoneFileIfNeeded cacheDir
+            |> extractWaterBodiesTileFromWorldCoverTileIfNeeded cacheDir
+            |> function
+                | CachedTileLoaded tileHeightsArray ->
+                    // todo 20: simplify water bodies
+
+                    tileHeightsArray
+                    |> Option.map (fun tileHeightsArray ->
+                        let downsampledWaterBodiesTile =
+                            tileHeightsArray
+                            |> downsampleWaterBodiesHeightsArray hgtSize
+
+                        let demWaterBodiesTile =
+                            downsampledAw3dTile
+                            |> encodeWaterBodiesInfoIntoDem
+                                downsampledWaterBodiesTile
+                            // extend the heights array with one additional
+                            //  row and column so it is compatible with the original
+                            //  SRTM HGT files
+                            |> extendHeightsArrayWithAdditionalRowAndColumn
+
+                        demWaterBodiesTile
+                        |> Hgt.writeHeightsArrayToFile hgtFileName
+                        |> ignore
+
+                        demWaterBodiesTile)
+                | TileNeedsToBeDownloaded _ ->
+                    invalidOp "Bug: this should never happen"
+                | TileDoesNotExistInWorldCover _ ->
+                    NotImplementedException(
+                        "The case when there is no WorldCover tile"
+                    )
+                    |> raise)
+        |> function
+            | Ok heightsArray -> heightsArray
+            | Error errorMessage -> invalidOp errorMessage
 
 
 let run (options: Options) : Result<unit, string> =

diff --git a/Demeton/Dem/Hgt.fs b/Demeton/Dem/Hgt.fs
@@ -11,7 +11,7 @@ open FileSys
 /// <summary>
 /// Reads HeightsArray data from a HGT-encoded stream.
 /// </summary>
-let readFromStream tileSize (stream: Stream) : DemHeight[] =
+let readHeightsFromStream tileSize (stream: Stream) : DemHeight[] =
     let inline readNextHeightFromStream (streamReader: FunctionalStreamReader) =
         let firstByte = streamReader.currentByte ()
 
@@ -69,8 +69,8 @@ let readFromStream tileSize (stream: Stream) : DemHeight[] =
 /// Reads the <see cref="HeightsArray"/> of a SRTM tile from
 /// a HGT file stream.
 /// </summary>
-let createDemTileFromStream tileSize tileId stream =
-    let srtmHeights = readFromStream tileSize stream
+let readHeightsArrayFromStream tileSize tileId stream =
+    let srtmHeights = readHeightsFromStream tileSize stream
 
     let cellMinX, cellMinY = tileMinCell tileSize tileId
 

diff --git a/Demeton/Srtm/Png.fs b/Demeton/Srtm/Png.fs
@@ -229,7 +229,7 @@ let convertZippedHgtTileToPng
 
             memoryStream.Seek(0L, SeekOrigin.Begin) |> ignore
 
-            Hgt.createDemTileFromStream SrtmTileSize tileId memoryStream |> Ok
+            Hgt.readHeightsArrayFromStream SrtmTileSize tileId memoryStream |> Ok
 
         match
             readHgtFileFromStream tileId zippedHgtFileName readHgtFileStream