How to design and create mobile maps using ArcGIS Desktop

Map viewing and data editing tasks that are performed in the field are quite different than those performed in the office. Form factors of the mobile device (including display resolution, key, rocker and/or stylus interaction), device memory and storage constraints, and the physical conditions in which the field tasks will be performed (direct sunlight, rain, darkness) can influence the design of your mobile map. Therefore, it is important that you design mobile maps with purpose and consider the workflows, tasks, and devices that the maps will be used with.

The following sections illustrate some key mobile map design considerations and detail how ArcGIS Mobile applications work with ArcGIS Desktop map symbology.

Design mobile maps for field use

When designing a mobile map, it is critical that you consider the tasks and workflows that will be performed in the field, where and when the application will be used (work environment conditions), and the vocabulary or terminology used by the field-workers. All these factors will dictate what layers of information are important for visualization, navigation, and collection/update in the field.

When working through the design of your mobile map, you should also consider how it will be deployed and managed in the field. Most mobile maps are composed of two primary types of layers—basemap layers and operational layers.

Basemap layers provide reference information used for visualization and/or navigation purposes (aerial imagery, streets, land parcel boundaries, and so on). Basemap layers are maintained by other departments within the enterprise or are acquired or purchased from an external source. There is no need to synchronize basemap layers, so they can be provided on mobile devices independent of a specific field project.

Operational map layers include layers that are updated in the field and/or provide information that may change during the course of a field project. Operational map layers are published as a GIS service and can be synchronized between the mobile device and a server. Using ArcGIS Mobile, you can post changes that are made from the field to the GIS server and receive changes that are made either in the office or by others while in the field.

Regardless of whether you start with an existing map or are creating a new map from scratch, you will need to consider factors such as the work environment conditions, display resolution of the device that you are taking to the field, the orientation of the device display (landscape or portrait), symbols chosen to represent features (mobile devices do not support all the symbols and styles that ArcGIS Desktop provides to you), and layer scale dependency.

Work environment conditions

The fieldwork environment may include intense sunlight, rain, or subzero snow conditions. Lighting conditions have a direct impact on the colors and symbols you choose when designing your map. In the office, you are designing maps under ideal conditions. The artificial light and large monitors used in the office enable the use of a wide range of colors and symbols. Unfortunately, this is something that you solve by trial and error. As a general guideline, design background layers to be as transparent as possible. The key to designing a successful mobile map is contrast and simplicity. If you have to display parcels, districts, or any area-based feature as background information, try your best not to fill the polygon, or if you need to, use simple colors. Use gray tones as much as you can and limit the amount of text that you need to display. Remember that what looks good in the office on a desktop computer often may not look good outside on a mobile device.

Overly Complex Map Design

Simple Map Design

Device form factors

You need to think about the form factor of the mobile device you are targeting with your application and what format maps will be displayed in (portrait or landscape). Most Pocket PC devices have a resolution of 320 x 240, but they can vary considerably. The monitor you are designing maps on is most likely 1024 x 780 or 1280 x 1024 or even higher. Resolution has a direct impact on scale dependency. It is very important to add scale dependency to the layers in your map so that you display layer content only when it is needed. This improves the clarity of your maps, and more importantly, it reduces the time it takes to draw the map.

You should set a visible scale for each layer. It is important to note that the ArcGIS Mobile applications do not honor the reference scale you set on a map, so symbols will not scale as you zoom in and out. When designing for the device form factor, it is recommended that you shrink the size of the map display window in ArcMap to mimic the size of the device and set scale dependency accordingly. You need to take this into consideration when determining the appropriate marker symbol size and line symbol thickness.

Shrink ArcMap display to approximate device resolution.

Map symbology

The symbols you choose to display geographic information will determine how effective the map is in your mobile application. If you are rebuilding an existing application or if paper maps are used in the field, try to use symbols that are familiar to the field-workers if possible. Keep the symbols you choose simple and remember that contrast is important in conveying the right information on your map. The challenge is that you are designing your mobile map using a desktop application that is meant for authoring maps to other desktop or Web applications—not field applications.

Symbology in ArcGIS can be categorized into the following types of symbols-: marker, line, fill, and text. ArcGIS Mobile supports a subset of the ArcGIS symbol sets. What is and is not supported is defined below.

Marker symbols

The mobile framework rasterizes marker symbols on the server and ships a bitmap representation to the client device cache. That means that all marker symbol types are supported. However, it is important to note that the map's reference scale is not supported, so you need to choose a size based on the scale at which the point feature is to be displayed.

Line symbols

When using line symbology, it is important to keep the symbols you choose for your mobile map simple, both for map clarity and for performance reasons.

ArcGIS Mobile supports simple line symbols, character line symbols, and hash line symbols, but it does not support marker line symbols nor line decorations like arrows on the endpoints of lines, for example.

Fill symbols

Where possible, you should avoid using a fill symbol for polygons that you draw on a mobile device as it often adds complexity to your map that is not needed on a mobile device.

ArcGIS Mobile supports simple fill symbols only. It also supports layered polygon symbols where the outline line symbol chosen could be a character or hash line symbol. The framework does not support other fill symbol types (picture, marker, line).

Text symbols

ArcGIS Mobile supports both labeling on a layer in ArcMap and annotation that is stored in a geodatabase in a mobile map. When labeling a mobile map, it is important to consider the font you choose and how it looks on the device you are authoring the map for. The text rotation angle is also important. For example, Tahoma 8pt font is a good font and size for labeling features on a Pocket PC or smart phone device. However, if the text is rotated, you should consider using a larger font size. Depending on the mobile device and its resolution, rotated labels might not display as nicely as you want. If you are writing custom applications using the ArcGIS Mobile SDK, the Map control has a property that lets you shut off label rotation.

ArcGIS Mobile does not support the justification properties for a map layer, and it does not support labeling using an expression. You must label directly from a single field value. In the example below, the text that is not supported is an expression that concatenates several fields to form a street address. To accomplish this, you will need to create a new field and calculate the value of the field equal to the concatenation of the existing fields.

Geodatabase annotation is supported in mobile maps. However, support is limited to text only. If you have callouts or graphics in your annotation feature, only the text will be displayed.

Data considerations

Field maps are often composed of one or two editable layers and a larger number of background layers. For example, pole inspection maps often contain pole, transformer, and transmission layers, which may be updated in the field. Pole inspection maps also include parcel or block boundaries, street centerlines, address information, and even imagery as supportive background information. Since both the layer information and the actual data are cached on the device, it is important for performance and storage reasons that all background data is as small and simple as possible. To simplify background data, first consider whether the background layer is required to complete the field task that the application is designed for.

If background layers are required, use simple symbology to represent features and use the generalization tools in ArcGIS Desktop to simplify the shape of background layers. In addition, use the Create Mobile Base Map geoprocessing tool to then create a basemap dataset from each of the background layers. This basemap dataset can be loaded onto the mobile device and used across field projects. You can then publish a map that contains the layers that need to be updated and synchronized between mobile devices and your GIS server.