How To: Optimize Map Image requests for speed
Instructions provided discuss how to create Map Image requests that return a map in the shortest amount of time.
This article applies to map images, not vector maps.
These are suggestions based on limited testing. Users must verify these results for their unique configuration. Internet connection speed, server speed, and other factors may make these tips less useful to the application.
Several factors can optimize Map Image requests. Suggestions at the top of the list return faster time differences than suggestions at the bottom.
- Small maps are fast maps, both in generation time and transmission time across the Internet. Slight changes in mapImageSize make significant differences in speed.
- When only creating street maps of the United States, use *.Streets.US rather than *.Streets.NA. The North American data sets contain more data that slow down the process.
- Be aware of zoom level. Street maps at medium zoom level are slowest, because they contain the most layers of data.
- Use the best map image format to retrieve the smallest map file. Large map image files take more time to transmit across the Internet. The default image type has been chosen with speed in mind.
- JPEG creates the smallest file size for imagery. For example, ArcWeb:GlobeXplorer.DOQQ.US and ArcWeb:ESRI.Satellite.World.
- GIF creates the smallest file size for line data. For example, ArcWeb:TA.Streets.NA and ArcWeb:NT.Streets.EU.
- PNG8 is always faster than PNG. PNG should only be used to create a 24-bit non-lossy image.
- Avoid unnecessary points, lines, and polygons. Geometry makes a significant difference in map speed. If attempting to display a large number of points on a map, consider using a thematic map to color regions based on how many points they contain, and then display points after the user zooms in to a smaller region.
- Keep the SOAP messages small. It takes time to parse and transmit SOAP across the Internet. Only include what is necessary.
- Do not request a legend unless it is going to be used. It makes a slight difference.