How to make your map draw faster
There are many contributing factors that may make your map slow to draw and, similarly, many ways to improve the drawing performance of your map.
This tutorial will describe different strategies you can use to make your map draw faster:
- Choose different hardware.
- Load less data on the device.
- Use different file types (for example, raster or SDC layers for background layers).
- Simplify the symbology used.
- Use scale-dependent rendering.
- Display the map in Quick Draw mode.
Choose different hardware
Choosing hardware that suits your project needs is the most critical step to a successful field project. If you really have to take a large amount of data into the field, use multiple sensors and data collection tools (for example, camera and a GPS and a range finder), and perhaps use navigation (such as StreetMap or ArcLogistics), a common Windows Mobile device may not be sufficient. In these cases, you must consider a tablet or laptop computer. There is a very large range of Windows Mobile devices suitable for mobile GIS, and you should clearly define your project needs before choosing a device.
For more information, refer to Selecting a Windows Mobile device.
Load less data on the device
The ever-increasing size of memory cards makes taking a lot of data into the field very tempting. Although it is not a problem to have a lot of data stored on a device or card, you may experience performance issues when you attempt to open the data all at once.
Think about breaking your data into logical portions (either by layers or area) so that you do not need to open entire large datasets at one time.
Use different file types
A good way to speed up your map is to clearly define the data you are editing (sometimes referred to as your operational data) separately from your background layers. Background layers are usually not edited in the field and are for reference only. You have a number of choices for background layers, but the best choice is to make them specific to your needs. If speed is your only priority, the best choices are as follows:
- Raster images (For more information on choosing the best raster format for your project, refer to Choosing a raster format.)
- SDC layers (The toolbox tool for creating SDC layers from your own data is no longer available in ArcMap 10.)
If you also need to be able to identify features in your background layers, you will need to consider using these:
- SDC layers
- Background shapefiles (Read-only shapefiles are the fastest drawing of all vector layer types.)
Simplify symbology used
Complex symbology types can affect the time it takes to draw your map. You can minimize this time by using complex symbology wisely. For example, if you have a detailed symbol that distinctly represents your point features (perhaps a multilayered symbol that varies only slightly between feature categories, for example, for values on a pipeline), you can create a feature layer that uses that symbol only at your main working scale. At larger scales (in this example, perhaps the whole length of the pipeline), the values can be represented as a simple symbol, perhaps just a basic circle. At large scales, the point features are more likely to be for reference only, so the symbology detail should be less important.
Use scale-dependent rendering
The section above describes using different symbology for layers at different scales. More specifically, you can also define the scale at which individual symbols are displayed. If you have features differentiated into categories (for example, features defined with a subtype in ArcMap), you can nominate what scale the individual symbol will be displayed at. For more information, refer to Working with scale-dependent symbology.
You can also set the scale at which an entire layer is displayed on the Layer Properties Scale tab.
Display the map in Quick Draw mode
Quick Draw mode provides you with a way to temporarily switch to an alternative drawing mode for your data. You can configure how you want each layer to be displayed when in Quick Draw mode via the table of contents. You can choose one of three states for each layer when Quick Draw mode is on:
- Keep the layer drawn in its full state (in other words, no change to the symbology).
- Display the layer in the optimized Quick Draw state
- Do not display the layer at all.
Layers selected for editing are drawn in full while in Quick Draw mode.
When ArcPad is experiencing low memory issues, Quick Draw mode is automatically enabled. Showing simplified symbology or less data is considered to be a better option than the map crashing.
If your vector layers use complex symbology, you will see an obvious change when in Quick Draw mode. Points are displayed as single pixels, lines are a single pixel in width using the same color as the full symbology, and polygons are single-pixel-width outlines (no fill pattern) using the same color as the outline of the full symbology.
Raster layers are also simplified in Quick Draw mode. Raster images are shown at a lower resolution.
Using Quick Draw mode is a good way to temporarily improve the speed of drawing your map.