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Query

The Query group on the Start tab is used for quick calculations and positioning while browsing a map. Common features include:

  • Measurement: interactively measure distance, area, or selected features.
  • Location: move the map view to a target position by longitude and latitude.
  • Coordinate conversion: convert point coordinates between different coordinate systems.

Measurement​

Measurement lets you draw interactively on the map to calculate distance or area, or measure selected features.

Supported Measurement Types​

  • Measure distance: draw a polyline and calculate the total length and segment lengths.
  • Measure area: draw a polygon and calculate the area and perimeter.
  • Measure features: calculate the length, perimeter, or area of the currently selected line or polygon features.

Supported Measurement Methods​

Measurement methods control the calculation model. Results may vary by coordinate system and scenario:

  • Geodesic
  • Planar (available in projected coordinate systems)
  • Rhumb line
  • Great ellipse

Distance Measurement Algorithms​

For the same polyline, the measured distance is usually the sum of its segment distances. The main difference between measurement methods is the spatial model used to calculate each segment distance.

  • Geodesic: calculates the shortest path length between two points on the reference ellipsoid. It is suitable for longitude/latitude coordinates, cross-regional measurement, and long-distance measurement, and is generally recommended as the default method.
  • Planar: calculates length on the current map's projection plane using Euclidean geometry. Results strongly depend on the projected coordinate system and measurement extent. It is suitable for small areas and scenarios that explicitly require projection-plane distance.
  • Rhumb line / Loxodrome: calculates the path length with a constant azimuth. In a Mercator projection, a rhumb line appears as a straight line. It is often used for navigation and heading-hold scenarios, but it is usually not the shortest distance between two points.
  • Great ellipse: uses a great-ellipse route on an ellipsoid as an approximate shortest-path calculation model. Results are usually very close to geodesic results, but may differ slightly over very long distances or in high-latitude areas.
How to choose

If you are not sure which method to use, choose Geodesic first. Choose Planar when you need projection-plane distance, Rhumb line when you need a constant-azimuth path, and Great ellipse when you need an approximate shortest path over a large area with simpler calculation.

astuce

If the current map uses a geographic coordinate system (longitude/latitude), Planar measurement is unavailable. Use Geodesic first, or use the measurement method required by your workflow.

Steps​

  1. Open Start > Query > Measurement, and select a measurement type from the drop-down menu: distance, area, or feature.
  2. In the dialog, select the measurement method and units as needed, such as meters/kilometers or square meters/square kilometers.
  3. Click on the map to start drawing, and continue adding points as prompted. End the interaction after you finish drawing.
  4. View the statistics in the Measurement results area. To measure again, click Clear.

Location (Coordinate Location)​

Location pans the map view to a specified position by longitude and latitude, and displays a center marker on the map.

Input Formats​

  • Decimal degrees: directly enter longitude and latitude, for example 116.3913, 39.9075.
  • Degrees, minutes, seconds: switch to Degrees, minutes, seconds format, and then enter degrees, minutes, and seconds separately.

Steps​

  1. Open Start > Query > Location.
  2. Enter the target longitude and latitude. Decimal degrees and degrees-minutes-seconds are supported.
  3. Click Location. The map pans to the target position and displays a marker.

Coordinate Conversion​

Coordinate conversion converts point coordinates between an input coordinate system and an output coordinate system.

Steps​

  1. Open Start > Query > Coordinate Conversion.
  2. In Input coordinates, enter X/Y values, east/north values, or longitude/latitude values.
  3. Select the input coordinate system and output coordinate system.
  4. Click Convert ==> to get the output coordinates. For reverse conversion, click <== Convert.
important

Coordinate conversion results depend strongly on the selected coordinate systems. If the result is unexpected, first check whether the input coordinate system and output coordinate system are selected correctly.