Documentation

Contents

1. Introduction
2. Map view and URL hooks
3. Gazetteer
4. Layers
5. Catchments

1. Introduction

Geolytix.xyz is a mapping web app designed to visualize and support outcome of spatial analysis carried out for a client. It is based on modular framework flexible for custom implementation and tailor-made analytical tools.

2. Map view and URL hooks

Map is the heart of the web app. It can be dragged and zoomed to desired location. Map extent is usually limited to selected locale.

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Fig. 2.1. Map view with app options on the left side. From top to bottom: gazetteer module, geolocation, increase/decrease zoom, link to documentation, logout, admin panel for accounts with admin rights.

All actions performed on the map will be tracked by the page URL where map view and all current settings will be stored as parameters. These will be also initially set if passed in the loaded URL.

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Fig. 2.2. URL with app settings stored as query parameters.

3. Gazetteer

Gazetteer is a core module that finds a desired location such as point of interest, geographic area or address depending on configuration. Search results are filtered by selected locale.

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Fig. 3.1. Country selection.

While typing in the search field gazetteer will match and list up to 10 best results such as name of a place, postal code, geographic area name or a street address returned by relevant data source.

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Fig. 3.2. Gazetteer results listing geographic areas.

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Fig. 3.3. Gazetteer results listing postal areas and districts.

On selection the map view will be set to selected geography.

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Fig. 3.4. Map view with SW11 postal district highlighted in green by gazetteer.

4. Layers

The web app supports several types of layers:

Available layers can be toggled active. Each layer has zoom levels set where layer becomes visible or hidden. It also supports different data sources for different zoom levels to allow cartographic generalization.

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Fig. 4.1. Layer manager view with loaded layers.

Multiple features across layers can be selected and their information displayed.

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Fig. 4.2. Selected features from two layers.

4.1. GeoJSON.

GeoJSON layer is a generic interactive or non-interactive vector layer. Layer will be visible at allowed zoom levels and loaded from relevant data source. Features can be selected in order to display available information.

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Fig. 4.1.1. GeoJSON layer with selected feature.

4.2. Mapbox Vector Tiles

MVT layer is a tile layer served directly from PostgreSQL and constructed from geometry data. like GeoJSON, this layer supports interactivity, zoom ranges, generalization and multiple selection. MVT layer supports categorized classification of features. Figure 4.2.1 shows retail places dataset with features categorized by retail place type.

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Fig. 4.2.1. MVT layer with categorized features.

4.3. Cluster

Cluster layer is a layer type designed to efficiently display dense point data with clustering logic based on zoom level. This layer also supports categorized legend with custom symbols.

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Fig. 4.3.1. Selected features from cluster layer showing retail points.

A clustering marker will also hold information on competitors. Each visible ring of the marker stands for diversity of company brands inside the cluster.

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Fig. 4.3.2 Clustering markers with their competition rings.

The URL will store information whether the locations module is enabled and specific location is selected.

Cluster layer also supports data editing and image upload, designed for site visits and on-site data collection.

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Fig. 4.3.3. Data editing form, example from Tokio, Japan..

4.4. Grid Surface

Grid surface module manages visualization of data represented as a grid such as demography or demand. This layer type is non-interactive but fully customizable with its variables, colour palette and number of classes.

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Fig. 4.4.1 Demographic grid surface in London area.

Two selected variables are visualized as size and colour accompanied by 2-dimensional legend. Available variables are shown in two dropdown lists.

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Fig. 4.4.2. Dropdown lists contain variables available for analysis and visualization.

alt text Fig. 4.4.3. Any two variables are selectable from dropdown lists.

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Fig. 4.4.4. Grid surface for the employed aged 25-29.

Grid surface will support analysis for site comparison and planning.

5. Catchments

This module returns demographic profile of an area with given travel time and travel mode around a selected point.

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Fig. 5.1. Catchment settings: walking or driving, travel time in minutes.

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Fig. 5.2. Catchment isochrone representing 45 minutes of travel time driving around location in West London along with area demographic grid surface.

Catchment GeoJSON object can be copied using Copy to clipboard button and reused within any other platform where GeoJSON format is supported. It can be pasted as a layer directly to QGIS.