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--- projects:fast_flow_accumulation [2024-08-03 10:12 pm] – removed - external edit (Unknown date) 127.0.0.1
+++ projects:fast_flow_accumulation [2024-08-03 10:12 pm] (current) – ↷ Page moved from fast_flow_accumulation to projects:fast_flow_accumulation hcho
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+====== Fast flow accumulation ======
+This project will improve the speed of flow accumulation.
+[[https://github.com/HuidaeCho/mefa|MEFA]]
+{{https://idea.isnew.info/publications/Memory-efficient%20flow%20accumulation%20using%20a%20look-around%20approach%20and%20its%20OpenMP%20parallelization%20-%20Graphical%20abstract.png}}
+===== Preliminary results =====
+  * Systems
+    * Linux 4.14.39 with SSD and 16GB RAM on Yoga 370
+    * ArcGIS on UNG Windows with SSD and 32GB RAM
+  * Data: Texas drain raster from [[efficient_longest_flow_path_algorithm|Efficient longest flow path algorithm]]
+  * Benchmark algorithms from https://github.com/zhouguiyun-uestc/FastFlow
+^ Program                                                      ^ Algorithm only (sec)  ^ Total (sec)  ^
+| ''FastFlow Zhou fdr.tif fac.tif''                            |  61                   |  87          |
+| ''FastFlow Wang fdr.tif fac.tif''                            |  174                  |  277         |
+| ''FastFlow Recursive fdr.tif fac.tif''                       |  178                  |  204         |
+| ''FastFlow Jiang fdr.tif fac.tif''                           |  304                  |  333         |
+| ''FastFlow BTI fdr.tif fac.tif''                             |  118                  |  144         |
+| TauDEM ''aread8 -p taud8.tif -ad8 tauad8.tif''               |  402                  |  607         |
+| TauDEM ''mpiexec -n 2 aread8 -p taud8.tif -ad8 tauad8.tif''  |  310                  |  514         |
+| ArcGIS Flow Accumulation                                     |                       |  478         |
+| Arc Hydro Flow Accumulation                                  |                       |  681         |
+| **Coming soon**                                              |  **48**               |  **107**     |
+| **Yet another coming soon**                                  |  **21**               |  **33**      |
+===== Results =====
+{{https://hcho.isnew.info/research/fig-fdr.png?400}}
+{{https://hcho.isnew.info/research/fig-benchmark-results-compute.png?400}}
+===== Discussion =====
+Too much overhead for raster I/O. Need to reimplement I/O using [[https://gdal.org/tutorials/raster_api_tut.html|GDAL]] or [[https://docs.fileformat.com/image/tiff/|from scratch]]? Done using GDAL.
+===== References =====
+  * [[http://skl.iswc.cas.cn/zhxw/xslw/201811/P020181116568187439544.pdf|A fast and simple algorithm for calculating flow accumulation matrices from raster digital elevation models]] (https://doi.org/10.1007/s11707-018-0725-9)
+  * [[https://gdal.org/tutorials/raster_api_tut.html|Raster API tutorial]]
+  * [[https://docs.fileformat.com/image/tiff/|TIFF - Image File Format]]
+  * [[https://medium.com/planet-stories/reading-a-single-tiff-pixel-without-any-tiff-tools-fcbd43d8bd24|Reading a Single TIFF Pixel Without Any TIFF Tools]]
+{{tag>projects}}