We have a large set of LIDAR data, in separate *.las file, each covering a small rectangular area. I wanted to create a polygon shapefile of the coverage of each tile for reference so I know which files to choose when we need a subset of the whole region. Using a bash “one-liner” and a simple function in Spatialite I had my polygon layer.
Continue reading Spatialite helps creating an index of LIDAR tiles
Nearly every new phone or tablet these days comes GPS enabled. And you can choose any of a slew of apps to capture GPS waypoints and tracks. But how do you get these data into a GIS system? Several apps save the GPS data into an sqlite database, so using Spatialite to convert the locations to spatial layers is a piece of cake.
Continue reading Get your phone GPS data into a GIS format
There are several PostGIS functions floating around to calculate the UTM zone EPSG code for points in Latitude/Longitude WGS84. However, Spatialite, based on Sqlite, does not support user created functions. So how can we get the same results in a Spatialite database?
Continue reading From Lat/Lon to UTM zone in Spatialite
I returned from a short bike outing with my ride captured as a GPS track. Along the way, I also grabbed the rest stops as waypoints. Both of these were downloaded from the GPS as *.gpx files. So I have tracks.gpx and waypoints.gpx. Now I want to push these layers straight into Spatialite, and do some calculations.
Continue reading Manipulating GPS tracks in Spatialite
Users of Ubuntu who want to use Spatialite for managing GIS layers are in luck. New updated packages have been released bringing to Ubuntu and derivatives all the new feature of spatialite 3.1.0.
Continue reading Spatialite on Ubuntu
Users of SQL databases often get tripped up when trying to update values in one table from another table. The method involves a subquery in the UPDATE statement to extract the values from the other (source) table. We’ll review how it’s done, both with simple attribute values, and with an update based on a spatial query.
Continue reading Spatialite- Updating one table from another
Spatialite, like any good spatial data management system, can build a spatial index for your layers. Using this index in your spatial queries will dramatically shorten the runtime for that query. The latest version of Spatialite offers a nice compact format for using a spatial index. To demonstrate, I created a point layer of 20,000 theoretical store locations, with sales data for each store, and a polygon layer of over 280 “local councils”. My mission it to sum up the total sales in each local council. So I need to find which stores are located in each local council and aggregate sales for those stores.
Continue reading Spatialite: Speedup your query with spatial indexing
The recent stable version of Spatialite, 3.0, supports linking to and importing Excel spreadsheet tables. Read on to see how it’s done.
Continuing my last post on using the spatialite tools and software on EL 6 and clones, here’s how I got the spatialite_gui to work.