This document discusses various techniques for optimizing map rendering when dealing with large amounts of location data. It recommends initially clustering close data together to simplify the user experience and reduce processing needs. Other optimizations include only rendering visible data by limiting to the current zoom level and using a quadtree data structure to more efficiently search for locations within a given area with each user interaction like panning or zooming. Code samples and external resources are provided for further exploring map optimizations.

1. Proprietary and
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Aurore Jard
Mobile Lead Developer
“Design for tomorrow”
“Deconstruct what you know”
“Simplify”
“Love what you did”
@AuroreJard

2. April 12, 2016
Don’t lose your way optimizing
maps rendering !
Talk : map optimizations ! Confidential

3. Requirements
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● Display
○ Data as locality
○ Zone on map
● User feature
○ Move
○ Zoom
● Access offline
Talk : map optimizations !

4. SDK Fight
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● Map
○ https://developer.apple.com/maps/
● Google
○ https://developers.google.com/maps/documentation/ios-sdk/
Talk : map optimizations !
Google Map VS Apple Maps

5. SDK Fight
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● Official documentation
○ Maps
○ Google iOS SDK
● Application also available on android : same experience on both
● Map more precise
● More possibilities
Talk : map optimizations !

6. First : easy steps
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● Get Data
● Display data
Talk : map optimizations !

7. What about really a lot of data ?
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8. First impressions
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● UI/UX remarks
○ Users are humans !
■ Adapt data according to zoom level
■ Zone, details : only on high level of zoom
■ Regroup data that eye can dissociate
● Performances
○ Avoid treating data you don’t see...
Talk : map optimizations !

9. First : clustering
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10. First : clustering
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● Regroup close data
○ easier user reading
○ Indication on number of location
in one group
● Clustering possibilities :
○ Grid based clustering
○ Distance based clustering
Talk : map optimizations !

11. Easy optimizations :
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● Grid based clustering
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12. Easy optimizations :
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● Distance-based Clustering
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13. Second : don’t treat invisible data
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● Limitation :
○ Zoom level
Talk : map optimizations !

14. Third : More optimization on sorting data
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● Why does it take so long ?
● Iterate over each location : 0(n)
● Every move from the camera (move, zoom) need to iterate again
Talk : map optimizations !
for location in locations {
if visibleBounds.containsCoordinate(location.position) {
// item should be display
}
else {
// ignore this location
}

15. Third : More optimization on sorting data
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● Reduce complexity by using QuadTree object & algorithms !
● Objective : subdivision of 2D space
● QuadTree = Tree with 4 leafs
Talk : map optimizations !

16. Third : More optimization on sorting data
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● Step 1 :
○ Build the tree from your initial data
○ Keep iteration on all locations on that process
■ o(n) but only once
Talk : map optimizations !

17. Third : More optimization on sorting data
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● Step 2 :
○ Search for locations in a specific area
■ Everytime you move / zoom
Talk : map optimizations !

18. Third : More optimization on sorting data
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● Why is it faster ?
○ For loop only done once at initialisation
○ Search then (user interactions)
■ O(h) (h = max depth of node in the tree)
Talk : map optimizations !
h=0
h=1
h=2
h=3

19. Links / Resources
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● Code :
○ Open Source library for clustering with Google Map iOS SDK
○ Display Large Amount of Data on iOS Map
● MapKit Apple Sample
○ Apple Sample clustering
● Other
○ QuadTree Interactive Explanations
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20. Have fun with maps ;)
Thanks !
ConfidentialTalk : map optimizations !

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