Deprecated

This module is now deprecated in favor of https://github.com/arno974/lizmap-altiProfil

Module Lizmap altitude

Module Lizmap d'ajout d'outils de requêtes sur les raster d'altitude stockés dans PostgreSQL

Import DEM to PostGIS

We support you have already installed and configured PostgreSQL with PostGIS extension, and a spatial database.

createdb altitude
psql -d altitude -c "CREATE EXTENSION postgis"

You can then import your DEM into your database

# Go in dem folder
# Adapt for your context
cd altitude/install/data/

# only if needed - Transform DEM into your working projection in meters
gdalwarp -co "COMPRESS=DEFLATE" -s_srs EPSG:4326 -t_srs EPSG:3857 srtm_montpellier_4326.tif srtm_montpellier_3857.tif

# Create SQL file with raster2pgsql
raster2pgsql -d -s 3857  -C -I -r -M srtm_montpellier_3857.tif -F -Y -t 200x200 public.srtm_montpellier > import_srtm_montpellier.sql

# Import data to postgis database
psql -d altitude -f import_srtm_montpellier.sql

Then import some test linestring

# Go in dem folder
# Adapt for your context
cd altitude/install/data/

# Import data to database and transform it into working projection
ogr2ogr -overwrite -a_srs "EPSG:3857" -f PostgreSQL PG:"dbname=altitude" test_linestring_3857.geojson -nln test_linestring  -lco GEOMETRY_NAME=geom

Test some PostgreSQL raster queries

-- Drape 2D geom to DEM and get 3D length and compare it to 2D length
SELECT ST_Length(geom) AS longueur_2D, ST_3DLength(drape_linestring('public.srtm_montpellier', geom, 50)) AS longueur_3D
FROM public.test_linestring
LIMIT 1;


-- Calcul denivels
SELECT c.c_climb, c.c_dhill, c.c_deniv, c.c_pclimb_max, c.c_pdhill_max
FROM public.test_linestring,
calcul_denivele(
    'public.srtm_montpellier',
    drape_linestring('public.srtm_montpellier', geom, 50),
    50
) AS c
LIMIT 1;

-- Requête pour récupérer le profil 3D d'une ligne 3D pour réaliser ensuite un graphique
WITH
source AS (
    SELECT drape_linestring('public.srtm_montpellier', geom, 50) AS geom_3d
    FROM public.test_linestring
    LIMIT 1
),
points3d AS (
    SELECT
    (ST_DumpPoints(geom_3d)).geom AS geom,
    ST_StartPoint(geom_3d) AS origin
    FROM source
)
SELECT ST_distance(origin, geom) AS x, ST_Z(geom) AS y
FROM points3d;