getting_started.md

i3dm.export getting started

In this document we run i3dm.export on a sample dataset of traffic signs (GeoJSON file). The generated instanced 3D tiles are visualized using a simple glTF box in a CesiumJS client.

Prerequisites

Some open source tooling is used in this tutorial:

• wget https://www.gnu.org/software/wget/

• Docker https://www.docker.com/get-started

• ogr2ogr https://gdal.org/programs/ogr2ogr.html

• psql https://www.postgresql.org/docs/9.2/app-psql.html

• Python 3 https://www.python.org/

Install i3dm.export

See releases for executables for Windows, Linux and MacOS

Download data

$ wget https://raw.githubusercontent.com/Amsterdam/mlvb/master/output/asset-registration/current_traffic_signs.geojson

Setup PostGIS

Start PostGIS database

$ docker run -d -e POSTGRES_PASSWORD=postgres -p 5432:5432 mdillon/postgis

Import traffic signs to PostGIS

$ ogr2ogr -f "PostgreSQL" PG:"host=localhost user=postgres password=postgres dbname=postgres" current_traffic_signs.geojson -nlt POINT -nln traffic_signs

PSQL into PostGIS

PSQL into PostGIS and do a count on the traffic signs:

$ psql -U postgres -h localhost

postgres=# select count(*) from traffic_signs;
 count
-------
 58999
(1 row)

Create instances table

We create a new table, with

• trees in epsg:4326;

• Box.glb as model;

• randomized scales;

• randomized horizontal rotations;

• for tags use fields 'id' and 'bevestiging' .

postgres=# CREATE TABLE traffic_signs_instances as (
	SELECT ogc_fid as id, 
	st_transform(wkb_geometry, 4326) as geom,
	1 +  random() as scale,
	random()*360 as rotation,
	'Box.glb' as model,
	json_build_array(json_build_object('id',ogc_fid), json_build_object('bevestiging',bevestiging)) as tags
	from traffic_signs
);

postgres=# CREATE INDEX geom_idx ON traffic_signs_instances USING GIST (geom);
postgres=# delete from traffic_signs_instances where st_x(geom) < 4.5 or st_x(geom)>5.0;
postgres=# exit;

Download Box.glb from https://raw.githubusercontent.com/Geodan/i3dm.export/main/docs/Box.glb

Run i3dm.export on instance table

$ i3dm.export -c "Host=localhost;Username=postgres;password=postgres;Port=5432" -t  traffic_signs_instances -f cesium

Here we visualize the traffic lights all instances as a simple red box (box.glb), but any glTF model can be used instead.

An 'output' directory will be created with a tiles subdirectory containing tileset.json and i3dm tiles.

Visualize in Cesium

Put the Cesium client (index.html and from directory samples\traffic_lights\cesium ) and the output folder with tiles on a webserver.

Result should look like:

Live demo: https://geodan.github.io/i3dm.export/samples/traffic_lights/cesium