Differences

This shows you the differences between two versions of the page.

--- nsw_lidar [2018/09/24 19:23] – allchin09
+++ nsw_lidar [2024/04/05 19:00] (current) – Add download bushwalking
@@ Line 1: / Line 1: @@
-Page for documenting NSW lidar processing
+====== Mapping from NSW Lidar with QGIS ======
-====== Intro ======
 NSW Spatial Services have undertaken a program to map all of NSW using lidar (light detecting and ranging)
-For details, see information on their [[http://spatialservices.finance.nsw.gov.au/mapping_and_imagery/environmental_spatial_programs|elevation program]]
+For details, see information on their [[http://spatialservices.finance.nsw.gov.au/mapping_and_imagery/environmental_spatial_programs|elevation program]].
+Elevation data can best be accessed through the [[http://elevation.fsdf.org.au/|Geoscience Australia ELVIS program]].
+It can then processed with a GIS such as [[https://www.qgis.org/en/site/index.html|QGIS]] to create useful topographic maps. Instructions below are specifically for use with QGIS, though the general outline may be useful for other GISs.
+====== Topics ======
+The original topics here have now been moved to their own pages.
+Any feedback/suggestions of improvements are welcome.
+===== Managing DEMs =====
+  * [[nsw_download_dems|Downloading DEMs]] - how to download DEMs from the ELVIS service
+  * [[nsw_merge_dems|Merging DEMs]] - how to merge DEMs in QGIS
+  * [[nsw_dems|Managing large DEMs]] - while data can be downloaded in an ad hoc manner, if you are regularly processing NSW DEMs, it is better to have the DEM tiles already downloaded. This page provides steps to do this in an automated manner.
+===== Topographic maps =====
+There are several primary data items for topographic maps that can be generated using the DEM data from the NSW Lidar.
+  * [[qgis_depressionless_dem|Hydrologically correct DEM]] - prior to further operations, it is usually important to make sure that your DEM is free of depressions. Otherwise these will mess up streams and possibly contours.
+Once you have a depressionless DEM, the following items can be generated:
+  * [[qgis_contours|Contours]]
+  * [[qgis_hydrology|Hydrology (Stream Network)]]
+  * [[qgis_slope|Slopes]] - while not a standard feature of topographic maps, this can be a simple way to identify cliffs
+  * [[qgis_clifflines|Clifflines]] - a work in progress
+===== Styles =====
+  * [[qgis_styling|Styling]] - download basic style files
+===== Automation =====
+  * [[qgis_basic_automation|Basic map creation]] - a set of PyQGIS scripts that will create (and optionally save) a basic topographic map. This map can be used in QField
+===== Mobile apps =====
+  * [[qgis_qfield|QField]] - QField is an excellent Android app for for viewing projects created with QGIS
+  * [[https://merginmaps.com/|Mergin Maps]] - (Previously Input App) is a mobile app compatible with QGIS
+===== Dumping Ground / WIP =====
+==== Resources ====
+  * [[https://www.tandfonline.com/doi/full/10.1080/23729333.2017.1300998|A design of contour generation for topographic maps with adaptive DEM smoothing]]
+  * [[http://www.jennessent.com/downloads/tpi-poster-tnc_18x22.pdf|Poster on TPI by Andrew D. Weiss]]
+[[https://grass.osgeo.org/grass78/manuals/addons/r.geomorphon.html|GRASS - r.geomorphon function information page]]. This is a different approach that could be taken for landform classification. Yet to be tested.
+[[https://docs.qgis.org/3.4/en/docs/training_manual/grass/grass_setup.html|Training lession for QGIS 3.4 on GRASS Setup and basic use]]. Specific GRASS setup is required to use any GRASS functions in QGIS.
+[[https://grasswiki.osgeo.org/wiki/Introduction_to_GRASS_GIS_with_terrain_analysis_examples|GRASS GIS example of terrain analysis using r.geomorphon]]
+[[http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.706.8909&rep=rep1&type=pdf|Geomorphons - a pattern recognition approach to classification and mapping of landforms]] paper.
+[[https://whiteboxgeospatial.wordpress.com/2014/12/25/a-new-form-of-multi-scale-topographic-position-visualization/|Multiscale topographic position - WhiteboxTools]] blog post.
+[[https://jblindsay.github.io/wbt_book/available_tools/geomorphometric_analysis.html#multiscaletopographicpositionimage|Multiscale topographic position image - WhiteboxTools function - user manual entry]]
+==== Method ====
+The below snip of Breakfast Creek makes use of TPI calculated from a LIDAR derived DEM. Only positive values for TPI as displayed, which indicate cliff-like features. It is then combined with contours and aerial imagery to convey the terrain of the area.
+{{:breakfast_creek_snip.jpg?400|TPI from LIDAR DEM combined with contours and imagery to show clifflines and terrain}}