erdas辐射定标

erdas辐射定标
英文回答：
Radiometric Calibration in ERDAS Imagine.
Radiometric calibration is a process that converts the digital values (DNs) in a raster image to reflectance values that are proportional to the amount of energy received by the sensor. This process is necessary to produce images that are accurate representations of the real world and can be used for a variety of purposes, such as land cover classification, vegetation analysis, and environmental monitoring.
There are two main types of radiometric calibration: absolute calibration and relative calibration. Absolute calibration uses a known reference target to measure the amount of energy received by the sensor. This method is typically used for high-precision applications, such as those requiring accurate measurements of surface
temperature. Relative calibration uses a set of images
taken over the same area at different times to determine
the relationship between the DNs and the reflectance values. This method is more commonly used because it is less expensive and time-consuming than absolute calibration.
The process of radiometric calibration in ERDAS Imagine involves the following steps:
1. Open the image to be calibrated.
2. Select the "Radiometric Calibration" tool from the "Tools" menu.
3. Specify the calibration method.
4. Select the reference image or target if using absolute calibration.
5. Click "OK" to perform the calibration.
Once the calibration is complete, the DNs in the image
will be converted to reflectance values. These values can then be used for a variety of purposes, such as land cover classification, vegetation analysis, and environmental monitoring.
中文回答：
ERDAS中辐射定标。

辐射定标是一个将栅格图像中的数字值（DN）转换为与传感器接收能量成正比的反光率值的过程。

此过程对于生成真实世界的准确图像表示是必要的，并且可用于各种目的，如土地覆盖分类、植被分析和环境监测。

辐射定标主要有两种类型，绝对定标和相对定标。

绝对定标使用已知的参考目标来测量传感器接收的能量。

这种方法通常用于高精度应用，例如需要准确测量表面温度的应用。

相对定标使用在同一区域上在不同时间拍摄的一组图像来确定DN与反射率值之间的关系。

这种方法更常用，因为它比绝对定标更便宜且更省时。

ERDAS Imagine中辐射定标的过程涉及以下步骤：
1. 打开要校准的图像。

2. 从“工具”菜单中选择“辐射定标”工具。

3. 指定校准方法。

4. 如果使用绝对定标，请选择参考图像或目标。

5. 单击“确定”执行定标。

定标完成后，图像中的DN将被转换为反射率值。

然后，这些值可用于多种目的，例如土地覆盖分类、植被分析和环境监测。