Color Balance

Usage Instructions

When there is a significant color difference between one tilt photogrammetry 3D model and other tilt photogrammetry 3D model data, you can use the Color Balance function to adjust the color of the selected data, thereby achieving consistent color across all data.

Function Entrance

  • 3D Geographic Design Tab -> Tilt Photogrammetry Data Operations -> Color Balance Button

Operational Steps

  1. Create a new spherical scene. Right-click "Scene" in the Workspace Manager and select "New Spherical Scene".
  2. Load 3D tiles. Select the General Layer in the Layer Manager, right-click and choose "Add 3D Tile Layer", or in the Scene tab, within the Data group, click the Tile drop-down button and select "Load Tile..." from the menu.
  3. Select the 3D tile layer in the Layer Manager, right-click and choose "Quickly Locate to This Layer". Hold the mouse wheel in the scene window to adjust the camera to a perspective suitable for observing the data.
  4. In the 3D Geographic Design tab, within the Tilt Photogrammetry Operations group, click the Color Balance button. The "Color Balance" panel will pop up on the right side of the software. The specific parameter settings are as follows:
    • Layer List: Displays all layers in the current scene that contain tilt photogrammetry 3D model data. Select the data to be adjusted from the list as needed.
    • Use the Import button to load a JSON file (*.colorAdj) recording color balance parameters and apply it to the specified data. Use the Export button to save the color balance parameter file to a specified path.
    • Use the Effect Visibility Toggle button to control whether the adjusted color balance parameters are applied to the data.
  5. Brightness/Contrast Settings: Click the Brightness/Contrast button, and the Brightness/Contrast module will appear below the panel. Adjust the sliders behind Brightness and Contrast to globally modify the lightness and color contrast of the data.
  6. Hue/Saturation Settings: Click the Hue/Saturation button, and an adjustment module will appear below the panel for fine-tuning the hue, saturation, and lightness of specific color ranges.
    • The checkbox in front of the module controls whether its parameters are active. The Delete button removes the module.
    • Color Selection: Choose the color range to adjust via the dropdown list. Options include: Master (All), Reds, Yellows, Greens, Cyans, Blues, and Magentas.
      • Selecting Master applies adjustments to all colors.
      • Selecting Reds/Greens/Blues adjusts the Red/Green/Blue channel (primary colors) of the data color.
      • Selecting Cyans/Magentas/Yellows adjusts the Cyan/Magenta/Yellow channel (complementary colors) of the data color.
    • Hue: Changes the color appearance. Dragging the slider shifts the selected color range on the color wheel.
    • Saturation: Controls the vividness of colors. Higher values increase saturation, making colors more intense. Lower values make colors closer to gray.
    • Lightness: Controls the relative brightness of colors. Increasing lightness brightens colors; decreasing it darkens colors.
    • You can enable multiple Hue/Saturation modules to adjust the hue, saturation, and lightness of different colors separately.
  7. Selective Color Settings: Click the Selective Color button, and an adjustment module will appear below the panel. This module is based on the CMYK (Cyan, Magenta, Yellow, Black) color model, changing the appearance of specific colors by adjusting the proportion of these four components.
    • The checkbox in front of the module controls whether its parameters are active. The Delete button removes the module.
    • Color Selection: Choose the color range to adjust. Options include: Neutrals (colors without hue), Reds, Yellows, Greens, Cyans, Blues, Magentas, Whites, Blacks. Note: Color selection here is based on CMYK color composition and targets pixels dominated by that composition color, not the visual color.
    • Component Adjustment: Use the sliders behind Cyan, Magenta, Yellow, and Black to increase or decrease their proportion in the selected color.
    • Adjustment Principle: Increasing one color is equivalent to decreasing its complementary color. For example, increasing Cyan in "Reds" actually reduces red, making it darker or grayer; decreasing Cyan increases red.
    • You can enable multiple Selective Color modules to adjust different color ranges separately.
  8. Vibrance Settings: Click the Vibrance option, and an adjustment module will appear below the panel to make color adjustments more natural.
    • The checkbox in front of the module controls whether its parameters are active. The Delete button removes the module.
    • Vibrance: Intelligently adjusts color vividness, with a range of [-100,100]. A higher value boosts saturation in less saturated areas while protecting already highly saturated areas, avoiding oversaturation and making colors more vibrant and natural without easily causing color clipping. A lower value reduces overall saturation but does not completely desaturate.
    • Saturation: Evenly adjusts the vividness of all colors, with a range of [-100,100]. A higher value simultaneously enhances the saturation of all colors, creating a strong visual impact but easily causing color clipping and loss of detail in originally vivid areas. A lower value simultaneously reduces the saturation of all colors, moving closer to black and white.
  9. Levels Settings: Click the Levels option, and an adjustment module will appear below the panel for precise control over the tonal range and color balance of the image.
    • The checkbox in front of the module controls whether its parameters are active. The Delete button removes the module.
    • Color Channel: Select the color channel to affect from the dropdown list. Options include: RGB, R, G, B.
      • RGB: Affects the Red, Green, and Blue channels simultaneously, primarily adjusting the overall lightness and contrast of the image.
      • R (Red), G (Green), B (Blue): Adjusts the tonal distribution of a single color channel individually.
    • Input Levels: Controls which brightness values in the data will be mapped to the darkest, middle, and brightest, thereby enhancing or reducing contrast.
      • Shadows (Black Point): Sets the mapping point for the darkest parts of the data. Parts below this value will be mapped to pure black.
      • Midtones (Gamma): Adjusts the brightness distribution of midtones, with a range of [0.01,9.99]. A smaller value brightens the midtones, lifting the overall data while affecting highlights less. Conversely, a larger value darkens the midtones, darkening the overall data while affecting shadows less.
      • Highlights (White Point): Sets the mapping point for the brightest parts of the image. Parts above this value will be mapped to pure white. The range is [4,255]. A larger value makes highlight areas brighter, increasing overall image contrast; a smaller value makes highlight areas darker, potentially recovering overexposed details.
    • Output Levels: Limits the brightness output range of the adjusted data.
      • Shadows: Limits the brightness value of the darkest pixel in the output data (original pure black is mapped to this value). The range is [0,255]. A larger value brightens the darkest areas, lifting shadow regions and making dark details more visible, but reduces contrast.
      • Highlights: Limits the brightness value of the brightest part in the output data (original pure white is mapped to this value). The range is [0,255]. A smaller value darkens the brightest areas, dimming highlight regions and preserving brightness details, but reduces contrast.
  10. Curves Settings: Click the Curves option, and an adjustment module will appear below the panel, allowing for precise control over image contrast and tone by adjusting the luminance mapping curve.
    • The checkbox in front of the module controls whether its parameters are active. The Delete button removes the module.
    • Color Channel: Select the color channel to affect from the dropdown list. Options include: RGB, R, G, B.
      • RGB: Affects all color channels simultaneously, primarily adjusting the overall lightness relationships and contrast of the data.
      • R (Red), G (Green), B (Blue): Adjusts the luminance curve of a single color channel individually.
    • The curve icon typically uses a histogram as the background. The histogram displays pixels at different brightness levels in the data. Adjust by clicking or dragging a control point on the curve.
    • Input: The horizontal axis of the histogram represents input, indicating the original brightness corresponding to that point in the data.
    • Output: The vertical axis of the histogram represents output, indicating the new brightness to which that original brightness is mapped after adjustment.
  11. After setup is complete, the adjustment effects will be displayed in real-time. Parameters can only be exported and saved. Parameters are not retained after closing the scene; you need to reapply them to the data by importing the saved parameter file.