Thermodynamic diagram

Instructions for use

Thermal map is a kind of map expression method to describe the distribution, density and change trend of people through color distribution, so it can intuitively present some data that are not easy to understand or express, such as density, frequency, temperature and so on.

The heat map layer can create a buffer for each discrete point, and then fill the buffer for each discrete point from the inside to the outside, from light to dark, with a progressive grayscale band (the complete grayscale band is 0 to 255); because the grayscale values can be superimposed (the larger the value, the brighter the color, and the whiter it appears in the grayscale band). In practice, any channel in the ARGB model can be selected as the superimposed gray value), so that the gray value can be superimposed for the area with buffer crossing, so the more the buffer crossing, the larger the gray value, and the hotter the area; The thermal map is implemented by mapping colors from a band of 256 colors (e.g., iridescence) indexed by the superimposed gray values, and recoloring the image. In general, the dot density state in the thermal map layer is displayed from cool to warm colors. For the mapping principle of thermal map, you need to open Alpha Channel in the map.

In addition to reflecting the relative density of point elements, the thermal map layer can also represent the point density weighted according to the attribute, so as to consider the contribution of the weight of the point itself to the density.

The thermal map layer, which changes as the map zooms in or out, is a dynamic grid surface. For example, draw the thermal map of the visitor flow of the national tourist attractions. When Zoom In, the thermal map can reflect the distribution of the visitor flow of the tourist attractions in a province or a local area.

SuperMap only makes thermal maps for point data and generates thermal map layers.

Function entrance

In Layer Manager, select the point data layer for which you want to make a thermal diagram:

  • On the Thematic Map tab-> Aggregate Map group-> click the Thermodynamic Map button.
  • Right click and select Create Thematic Map.. in the pop-up Context Menu. In the pop-up Create Thematic Map dialog box, select Aggregate Diagram-> Thermodynamic Diagram.

Operation steps

  1. A thermal map theme layer is generated in Layer Manager.
  2. Select a thermal map layer, and right-click the Modify Thematic Map command to pop up the Layer Properties panel on the right side of Map, which displays the setting information of the current thermal map.
  3. In the Layer Properties panel, you can modify the settings of basic functions such as Display Control and Change Dataset for thermal layers.
    • Display Control: supports viewing and setting of layer visibility, Layer Name, Layer Caption, transparency, and maximum and Minimum Visible Scale.
      • Visibility: In the Layer Properties panel, you can Uniform SettingsLayer Group the visibility of All Layers in. If the Displayable check box is selected, All Layers under the selected Layer Group will be visible; if the Displayable check box is not selected, All Layers under the selected Layer Group will not be visible.
      • Layer Name: used to display the name of the selected Layer Group. The name of the Layer Group cannot be modified. The name of the Layer Group is the Unique identifier of the Layer Group in the map where the group is located.
      • Layer Caption: The text box on the right is used to display the title of the selected Layer Group. You can modify the title of a Layer Group. After modification, the Show Name of the Layer Group in the Layer Manager changes, but the name of the Layer Group does not change.
      • Transparency: The spin box and spin button on the right set the transparency of the current layer. Users can enter the transparency value directly, or click the spinner button to the right of the tab to adjust the transparency and view the setting results in real time. The default transparency value is 0, which means the layer is completely opaque. As the value increases, the layer becomes more transparent. When the transparency value is set to 100, the layer is completely transparent. The transparency value is an integer between 0 and 100.
      • Minimum Visible Scale: The combo box is used to set the Minimum Visible Scale of All Layers in the Layer Group. After a layer Group Settings Minimum Visible Scale, if the map's scale bar is smaller than Minimum Visible Scale of the layer's Group Settings, All Layers in the Layer Group will not be visible. You can use the spin box to the right of Minimum Visible Scale to enter a scale value, such as 1:500000, or Current MapScale Settings to Minimum Visible Scale. You can also click the Drop-down Button on the right and select Scale Settings as the Minimum Visible Scale. The drop-down options are 8 scales from the default 1:5000 to 1:1000000; If Fixed Scales is set for the map, the optional scale of the drop-down item is the fixed scale.
      • Maximum Visible Scale: The combo box is used to set the Maximum Visible Scale of All Layers in the Layer Group. After a layer Group Settings Maximum Visible Scale, if the map scale is larger than Maximum Visible Scale of the layer's Group Settings, All Layers in the Layer Group will not be visible. You can use the spin box to the right of Maximum Visible Scale to enter a scale value, such as 1:500000, or Current MapScale Settings to Maximum Visible Scale. You can also click the Drop-down Button on the right to select a Scale Settings as the Maximum Visible Scale. The drop-down options include 8 scales from the default 1:5000 to 1:1000000; If Fixed Scales is set for the map, the optional scale of the drop-down item is the fixed scale.
    • Change Dataset: Click the drop-down arrows to the right of Datasource and Dataset, respectively, and select the Dataset to be referenced and the Datasource where the Dataset is located. See: Change Dataset for more information .
  4. Parameter Settings: You can set parameters such as core radius, Weight Field, Color Scheme, color gradient blur, maximum color weight and maximum value of the thermal map layer. The settings of the above parameters will determine the Display Effects of the thermal map. The details are as follows:
    • Core Radius: Sets the influence radius for discrete points. The nuclear radius plays a role in the thermodynamic diagram as follows:
      • The thermal map establishes a buffer for each discrete point based on the set core radius value. The unit of nuclear radius value is: screen coordinate;
      • After establishing a buffer zone for each discrete point, filling the buffer zone of each discrete point from inside to outside and from shallow to deep by using a progressive gray band (a complete gray band is 0 to 255);
      • Because gray values can be superimposed (the higher the value, the brighter the color, and the whiter it appears in the gray band). In practice, any channel in the ARGB model can be selected as the superimposed gray value), so that the gray value can be superimposed for the region with buffer crossing, so the more the buffer crossing, the larger the gray value, and the hotter the region;
      • The thermal map is implemented by mapping colors from a band of 256 colors (e.g., iridescence) indexed by the superimposed gray values, and recoloring the image.
    • Weight Field: Determines the influence of a point on the density. The weight value of a point determines the influence of the point buffer on the density, that is, if the original influence coefficient of the point buffer is 1 and the weight value of the point is 10, the influence coefficient of the point buffer is 1 * 10 = 10 after the weight is introduced. And so on, the density influence coefficient of other discrete point buffers. After the weight is

      introduced, a new superimposed gray value index will be obtained, and then the specified color band will be used to color it, so as to realize the thermodynamic map of the weight.

      Note:: The field used as the weight must be a numeric field.

    • Aggregate: When the Weight Field is specified, you can specify the aggregation method of the field points. The program provides five aggregates, namely: average value, number, maximum value, minimum value and total value.
    • Set Color Scheme: The color schemes provided by the system are listed in the drop-down list of the combo box. Select the required color scheme, and the system will Color SchemeAutomatic Allocation the theme style corresponding to each rendering field value according to the selected color scheme.
    • Minimum color transparency: The first color box on the right shows the Transparent Display status of the current minimum color. Adjust the transparency of the minimum color through the value combo box on the rightmost side. The default transparency is 100, that is, completely transparent.
    • Maximum color transparency: The first color box on the right shows the Transparent Display status of the current maximum color. Adjust the transparency of the maximum color through the rightmost value combo box. The default transparency is 10.
    • Color mode: Support the user to select the color mode to be displayed, including HSB and RGB.
    • Color Gradient Blur: mainly adjusts the blur degree of the color gradient in the thermal map to adjust the rendering effect of the color band.
    • Maximum color weight: determines the proportion of the maximum color in the gradient color band. The larger the value is, the larger the proportion of the maximum color in the color band is.
    • Original Point Visible Scale: Set the visible scale range of the Point Dataset layer for generating the thermal map. Click the combo box Drop-down Button, and the program provides 10 types of scales. They are: 1:5000, 1:10000, 1:25000, 1:50000, 1:100000, 1:250000, 1:500000, 1:1000000, current scale, and System Default Scale. The user can also customize the input scale. It is convenient for the user to set the visible scale range of the original point according to the mapping requirements.
      • System Default Scale: The program will calculate a scale according to the current heat map as the visible scale of the original point. Raw points smaller than System Scale are not visible. Raw points larger than System Scale are visible.
      • Set to Current Scale: Set the scale of the current Map as the visible scale range of the Point Dataset layer. The original point smaller than current scale is invisible, and the original point larger than current scale is visible.
    • Extremum Value Settings:: Set the maximum value and minimum value when displaying the thermodynamic diagram, where the maximum value corresponds to the maximum value color, and the minimum value corresponds to the minimum value color, and construct the rendering color band according to the relationship between the two values. While other sections of Greater than Maximum Value are rendered in the maximum color, sections of Less than Minimum Value are rendered in the minimum color.
      • The extremum value of the view: Use the maximum and minimum values in the current view window as the maximum and minimum colors of the thermal map, so that the program will construct a color band according to the maximum and minimum colors of the current view, and render the thermal map in color. (That maximum and minimum value for the current view will change depending on how the window is zoom in and out.)
      • The system extremum value: By default, the system will calculate a default maximum and minimum value of the thermodynamic diagram based on the current Map Scale (the system maximum and minimum value will change according to the change of Map Scale).
      • Customize the maximum value: Adjust the distribution of the maximum value color and the minimum value color of the thermal diagram by customizing the maximum value and the minimum value. According to the relationship that the maximum value corresponds to the maximum value color set by the user and the minimum value corresponds to the minimum value color, a rendering color band is constructed to perform color rendering on the thermodynamic map.
  5. A thermodynamic diagram based on Point Dataset is made through the above Parameter Settings.

Application example

The thermodynamic map intuitively describes the spatial distribution and change trend of geographical phenomena through color distribution, which is usually not easy to express, such as density, temperature, frequency, etc. The following figure is a thermodynamic map reflecting the distribution of cultural and educational institutions in China based on the point data of the distribution of cultural and educational institutions in China.

Data Path SuperMap Sample Data SampleData-> AggregationMap-> HeatMap

Figure: Thermal map of the distribution of educational institutions in China