Happy #MapInfoMonday!
Today, we will look at a preference that will speed up the rendering of point data in your maps:
Fast Symbol Rendering. We will also discuss when this preference should not be used.
What is Fast Symbol Rendering?
Fast Symbol Rendering is an improvement we made to the way MapInfo Pro renders point layers.
Typically what happens is that all the points inside the map extent would get rendered one at a time and this would be saved to a bitmap which finally would be shown on the screen.
The improvement we put in place checks if a point already has been rendered at a given pixel before rendering the point. This check prevents MapInfo Pro from rendering multiple points on top of each other as you wouldn't be able to see this anyway.
The benefit of this simple check is a much faster rendering time for point layers.
How much faster is it?
The more points your table holds, the better the improvement. And the closer the points are, the better the improvements.
Let's look at an example. Below you can see a map with the POI data from the
Precisely World Point of Interest dataset for Austria.
This dataset holds close to 1.4 million points with more than 50 columns. The file size of the .DAT file is close to the 2GB limit of a Native Tab file.
When I open a workspace with the map below in MapInfo Pro v2019 with the
Fast Symbol Rendering preference set to off, it takes 15 seconds to load and display the points on a map. If I turn on
Fast Symbol Rendering, MapInfo Pro can display the points in less than 6 seconds.
If I compare this to MapInfo Pro v15.0, the difference is even bigger. MapInfo Pro v15.0 takes 30 seconds to open the workspace and display the points on the map.
Where do I manage Fast Symbol Rendering?
Fast Symbol Rendering is one of the
Output preferences. On the
Backstage (the
Pro tab), go to
Options and click on
Output Settings.
You find
Fast Symbol Rendering on the
Display tab in the
Output Preferences dialog.
What should you be aware of when using Fast Symbol Rendering?
When you are rendering the entire layer with the same symbol, you are not running into any issues with the
Fast Symbol Rendering. In these situations, you can't tell how many points would be on top of each other anyway as they are rendered as one point, one symbol.
The problems can arise if you render your layer with different symbol styles, especially if you can see through some of these symbol styles. In these cases, one symbol could be rendered with one symbol style, and another point at the same location should be rendered with a different symbol style that wouldn't hide the symbol style of the previous symbol style.
Two issues we often hear of are the highway shields in the
Precisely Street dataset and using the dispersed symbols.
Here's a map rendered without
Fast Symbol Rendering.
Here's the same map rendered with
Fast Symbol Rendering.
In the image below, I have highlighted a few places where you can see a difference. Two points are at the same spot, the same pixel, but only one of them is drawn.
As described above,
Fast Symbol Rendering is a preference that affects all maps and all layers. It's either turned on or it is turned off for the current session.
For the upcoming MapInfo Pro v2021 coming later this year, we are investigating if we can change this from being a session-wide setting to a setting either per map or maybe even per layer.
What's your experience using
Fast Symbol Rendering?
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Peter Horsbøll Møller
Principal Presales Consultant | Distinguished Engineer
Precisely | Trust in Data
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