Best Practices for Data

Set Zoom Layer for Data with Many Records

A map image that contains many 10,000s of geometries will render more slowly. Displaying large amounts of data is computationally more intensive as it requires Spectrum Spatial to retrieve a larger number of geometries from the table or database and render them on the map. Also, when a map containing this number of geometries is shown, the base map is obscured, and the map can look cluttered.

We recommend applying appropriate zoom layer settings to the layer in MapInfo Pro before the Named Map is uploaded to Spectrum Spatial. Open the data in MapInfo Pro and make sure that the map Window is the same size as a map tile in Spectrum Spatial Analyst (approximately 512 x 512 pixels, it does not need to be exact). Zoom in until there are no more than around 10,000 (for polygons/lines) or 25,000 (for points) records for a layer at its densest location. Zoom layer settings should be added to ensure the layer is visible only from this level down.

Provide Alternative Ways to Show Information

Sometimes it is useful to see the pattern of distribution of density of data. For example, there may be 100,000s of customer records, and showing all of them shows their distribution. However, rendering a map which shows 100,000s of records is not performant.

An alternative approach would be to create a different layer to show density (perhaps a thematic map by county or another region, or a grid map). These approaches allow the data density to be shown much more performantly. The original customer layer can still be enabled when the user zooms in allowing them to get information on individual customer records if needed.

Complex Geometries

Some data has geometries with many 10,000s nodes. Flood boundaries are typical of this kind of data set, and some datasets can have polygons which have over 400,000 nodes. When rendering a map even if the user is zoomed in if the complex feature is within the map view, then all of the nodes will be returned to Spectrum Spatial when rendering the map.

We recommend thinning geometries or splitting them.

Thinning Complex Geometries

Where the level of detail is not needed, we recommend that complex geometries are thinned using MapInfo Pro before uploading them. As an example, if your data contains detailed polygon boundaries for regions with 100,000’s of nodes for each region, then thinning the data improves map render time significantly. If in this example the regions of a country will be displayed as a thematic map, such as a map of French departments, then thinning data to contain 1,000 nodes per region does not affect map detail.

Splitting Complex Geometries

Where the level of detail is needed, we recommend that complex geometries are split into multiple smaller geometries using MapInfo Pro before uploading them. Depending on the type of data and analysis, geometry records that contain more than 30,000 to 50,000 nodes may benefit from splitting. As an example, when analyzing flood boundaries that display at the property level. To split a large number of records in MapInfo Pro, create a grid and split the data using the grid.