ort We are hiring Marco Duiker – SkyGeo Delivering high resolution deformation maps with high performance and extensive processing
The InSAR concept Acquisition 1 Acquisition 2
The InSAR concept Centimeters Acquisition 1 Phase difference Acquisition 2
Resulting data properties • Movements measured with mm precision • Measurement interval 4-35 days • Data available from 1992 • Needs hard consistently reflecting surfaces • Measurements are relative (in space and time) • Pixel size from 3x3m to 7x26m • Positional accuracy (X,Y,Z) of reflector 1-2m • Measurement in direction of satellite
Injection monitoring
Gas pipeline monitoring
Municipality maintenance planning
Travel Guide The customer portal • We deliver ● Mapping services: WMS(-C) ● Data services: WFS ● Processing services: WPS ● Data: csv-files • We provide viewers with the ● Data ● Meaningful tools • How do the OGC standards keep up with our needs?
Travel Guide Interesting features Explore data by fjltering
Trip Report Hidden Gem: WMS-dimensions • WMS-dimensions: not only for time or elevation • Is advertised in the Capabilities document • Provides a way for subselecting data in the GetMap request ● (not restricted to the attribute which is used for classification) • Eg: &DIM_PNT_QUALITY=0.76/1 ● Gives all features with 0.76 <= pnt_quality <= 1
Travel Guide Interesting features Explore data by time slider
Trip Report Time slider • Simpl subtraction of cumulative deformation on two dates • Easily done with runtime substitution • WMS-support: ● Vendor Specific Parameters ● Just add the start date and the end date to the request
Trip Report Interesting features: multiple styles • Customer needs that to gain good insight in the data • WMS-standard allows for defining multiple styles on a layer ● Different styles to: ● Stretch the colors over the values ● Select a point size ● Proves to be cumbersome: ● Lots of styles → very long mapfile, slower performance ● Not very user friendly • Alternative ● Setting point size and stretching via sliders ● WMS support: vendor specific parameters ● Cumbersome to do in Mapserver ● (requires rewriting the mapfile or using mapscript)
Travel Guide Interesting features Multiple styles alternative
Travel Guide Interesting features Explore data by query (spatial or attribute)
Trip Report Querying & downloading data • WFS-services provide quite a few ways to select and download data • Nice to do queries & display results on map • Slow in mapserver 6, much better in mapserver 7 • Still slow on large datasets (compared to a database query) ● Have a download file (csv) of the entire dataset handy
Travel Guide Interesting features data processing
Trip Report Processing data • WPS standard provides: ● A way to send a request for processing ● (send in data/ service url as well!) ● A way to send the response when done • PyWPS provides an implementation for the WPS-standard ● The processing: ● (Grass plugin for generic geo-spatial processing) ● Program in Python ● Not confined to the data served via WMS/WFS ● Queuing & killing tasks: write yourself (or use pyWPS 4.0)! ● Difficult (impossible?) to get fully functional without Apache & cgi ● Relatively easy to extend and/ or hack ● No proper support for sub-domain specific access ● (submitted a pull request which has lots of issues!)
Architecture: the requirements ● “Normal” mapping functionality + more unusual ones ● Fast (while doing 'live rendering') ● Reliable (24/7/365 & fool proof) ● Secure ● Scaleable ● Flexible with short time to market for new features ● maps data and analysis ● viewer and services (standards compliant !)
Trip Report KISS-proof Architecture
Trip Report KISS-proof Architecture Almost Everything is file based & tied to viewer context Customers & viewer contexts
Trip Report Deployment • Every application is in its own Docker container ● Providing its own execution environment ● Every application can be upgraded independently ● Multiple versions of same application • Containers are managed (orchestrated) ● Docker-compose • New servers are deployed by Fabric ● A python script sending all necessary commands over ssh
Trip Report Conclusions • OGC-standards come a long way in providing the necessary standards for a rich web application • Live rendering (assisted by some smart caching) comes a long way in giving a high-performance experience • Docker really helps in keeping things manageable and upgradeable
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