求The ERDAS Field Guide第一章内容

求The ERDAS Field Guide第一章内容
Preface
The ERDAS Field Guide is now being used as a textbook, lab manual, and training guide throughout the world.
The ERDAS Field Guide will continue to expand and improve to keep pace with the profession.
谢谢

Chapter 2 Vector Layers
本章教学要求：有关专业英语单词
Introduction
ERDAS IMAGINE is designed to integrate two data types, raster and vector, into one system. The vector data structure in ERDAS IMAGINE is based on the ArcInfo data model (developed by ESRI, Inc. ). This chapter describes vector data, attribute information, and symbolization.
You can use ArcInfo coverages directly without importing them.
记住 Figure 2-1: Vector Elements 中的英文词.
ArcGIS Integration
ArcGIS Integration is the method you use to access the data in a geodatabase. ERDAS IMAGINE has always supported ESRI data formats such as coverages and shapefiles, and now, using ArcGIS Vector Integration, ERDAS IMAGINE can also access CAD and VPF data on the internet.
Chapter 3
Raster and Vector Data Sources
本章教学要求：1、重点：Satellite data部分
2其余部分,仅要求标题有关专业英语单词
Introduction
This chapter is an introduction to the most common raster and vector data types that can be used with the ERDAS IMAGINE software package.
The raster data types covered include: （See text,
Importing and Exporting（不用理会)
Satellite Data
There are several data acquisition options available including photography, aerial sensors, and sophisticated satellite scanners. However, a satellite system offers these advantages:
• Easily processed and analyzed by a computer.
• Many satellites orbit the Earth, so the same area can be covered on a regular basis for change detection.
• Once the satellite is launched, the cost for data acquisition is less than that for aircraft data.
• Satellites have very stable geometry, meaning that there is less chance for distortion or skew in the final image.
Satellite System
A satellite system is composed of a scanner with sensors and a satellite platform. The sensors are made up of detectors.
（See the detailed in text）
Satellite Characteristics
The U. S. Landsat and the French SPOT satellites are two important data acquisition satellites. They have several characteristics in common:
• Both scanners can produce nadir views.
• They have sun-synchronous orbits, meaning that they rotate around the Earth at the same rate as the Earth rotates on its axis, so data are always collected at the same local time of day over the same region.
• They both record electromagnetic radiation in one or more bands. Multiband data are referred to as multispectral imagery. Single band, or monochrome, imagery is called panchromatic.
Figure 3-1 Multispectral Imagery Comparison
IKONOS（was launched in September of 1999）
The resolution of the panchromatic sensor is 1 m. The resolution of the multispectral scanner is 4 m. The swath width is 13 km at nadir.
Table 3-4: IKONOS Bands and Wavelengths
补：美DigitalGlobel (EarthWatch)公司的QuickBird（快鸟）图像,波段分布与IKONOS同,但pan和multispectral分辨率分别达0.6和2.4米,为民用卫星之最.
IRS (Indian Remote Sensing Satellite)
Landsat 1-5 (See the histoty in text)
Landsats 1, 2, and 3 are no longer operating, but Landsats 4 and 5 are still in orbit gathering data.
Landsats 1, 2, and 3 gathered Multispectral Scanner (MSS) data and Landsats 4 and 5 collect MSS and TM data.
MSS (Multispectral Scanner)
MSS data are widely used for general geologic studies as well as vegetation inventories.
Table 3-8: MSS Bands and Wavelengths
TM （Thematic Mapper）
The TM scanner is a multispectral scanning system much like the MSS. TM has higher spatial, spectral, and radiometric resolution than MSS.
The spatial resolution of TM is 28.5 × 28.5 m for all bands except the thermal (band 6), which has a spatial resolution of 120 × 120 m.
Table 3-9: TM Bands and Wavelengths
Landsat 7
launched in 1999, uses Enhanced Thematic Mapper Plus (ETM+) to observe the Earth.
Table 3-10: Landsat 7 Characteristics
NLAPS
NOAA Polar Orbiter Data
AVHRR
See Table 3-11: AVHRR Bands and Wavelengths, also Figure 3-1.
OrbView-3 (US) 类似 IKONOS.
SeaWiFS（Sea-viewing Wide Field-of-View Sensor）
SPOT
The sensors operate in two modes, multispectral（20m） and panchromatic (10m).
Also see Figure 3-1.
Panchromatic
XS (see table 3-14: SPOT XS Bands and Wavelengths)
SPOT 4 (was launched in 1998)
增加一个1.58 to 1.75 μm的近红外波段；See table 3-15.
补：SPOT 5—— Panchromatic 波段达2.5米分辨率.
补：我国资源一号卫星CBERS
Radar Data
Researchers are finding that a combination of the characteristics of radar data and visible/infrared data is providing a more complete picture of the Earth. In the last decade, the importance and applications of radar have grown rapidly.
Advantages of Using Radar Data
• Radar microwaves can penetrate the atmosphere day or night under virtually all weather conditions. 全天候
• Under certain circumstances, radar can partially penetrate arid and hyperarid surfaces, revealing subsurface features of the Earth.
• For research on bodies of water.
Radar Sensors
Radar images are generated by two different types of sensors:
SLAR (Figure 3-4)
SAR — uses a side-looking, fixed antenna to create a synthetic aperture.
Active and Passive Sensors
An active radar sensor gives off a burst of coherent radiation that reflects from the target, unlike a passive microwave sensor which simply receives the low-level radiation naturally emitted by targets.
Applications for Radar Data
• Geology
• Classification
• Glaciology
• Oceanography
• Hydrology
• Ship monitoring
• Offshore oil activities
• Pollution monitoring
Image Data from Aircraft
This is useful if there is not time to wait for the next satellite to pass over a particular area, or if it is necessary to achieve a specific spatial or spectral resolution that cannot be attained with satellite sensors.
GPS Data
Chapter 4 Image Display
本章教学要求：1、重点：RGB & Displaying Raster Layers 部分
2 、Using the Viewer 部分,结合实习1
Introduction
This section defines some important terms that are relevant to image display. This may differ from other systems, such as Microsoft Windows NT.
The display hardware contains the memory that is used to produce the image. This hardware determines which types of displays are available (e.g., true color or pseudo color) and the pixel depth (e.g., 8-bit or 24-bit).
Display Memory Size
• display resolution—the number of pixels that can be viewed on the display screen.
• the number of bits for each pixel or pixel depth.
Pixel（file pixel & display pixel）
• the data file value(s) for one data unit in an image
• one grid location on a display or printout
To display an image, a file pixel that consists of one or more numbers must be transformed into a display pixel with properties that can be seen, such as brightness and color.
Colors（RGB）
Red, green, and blue can be added together to produce a wide variety of colors, are therefore the additive primary colors.
（三原色和三补色,及其它颜色特性,推荐阅读彭书 58-66页）
color guns
On a display, color guns direct electron beams that fall on red, green, and blue phosphors. The phosphors glow at certain frequencies to produce different colors.
The combination of the three color guns, each with 28 possible brightness values, yields 224 or 16,777,216 possible colors for each pixel on a 24-bit display. (line 7-9, page 110)
Colormap and Colorcells
A colormap is an ordered set of colorcells, which is used to perform a function on a set of input values. To display or print an image, the colormap translates data file values in memory into brightness values for each color gun.
（SEE Table 4-1）
Colorcells
There is a colorcell in the colormap for each data file value. he red, green, and blue values assigned to the colorcell control the brightness of the color guns for the displayed pixel.
Colormap vs. Lookup Table
The colormap is a function of the display hardware, whereas a lookup table is a function of ERDAS IMAGINE.
Display Types
• 8-bit PseudoColor
• 24-bit DirectColor
• 24-bit TrueColor
32-bit Displays
A 32-bit display is a combination of an 8-bit PseudoColor and 24-bit DirectColor, or TrueColor display.
8-bit PseudoColor： a colormap with 256 colorcells.
This display grants a small number of colors to ERDAS IMAGINE. It works well with thematic raster layers containing less than 200 colors and with gray scale continuous raster layers. For image files with three continuous raster layers (bands), the colors are severely limited.
24-bit DirectColor or 24-bit TrueColor
两种方式（Colorcell or color gun）达到24位彩色实时显示的目的：
enables you to view up to three continuous raster layers (bands) of data at one time, creating displayed pixels that represent the relationships between the bands by their colors.
PC Displays
ERDAS IMAGINE for Microsoft Windows NT supports the following visual type and pixeldepths:
• 8-bit PseudoColor
• 24-bit TrueColor
8-bit PseudoColor
An 8-bit PseudoColor display for the PC uses the same type of colormap as the X Windows 8-bit PseudoColor display.
24-bit TrueColor
A 24-bit TrueColor display for the PC assigns colors the same way as the X Windows 24-bit TrueColor display.
Displaying Raster Layers
Continuous Raster Layers
An image file (.img) can contain >3 continuous raster layers; Therefore, when displaying an image file with continuous raster layers, it is possible to assign which layers (bands) are to be displayed with each of the three color guns.
Band assignments are often expressed in R,G,B order. E.g.
• Landsat TM—natural color: 3, 2, 1
• Landsat TM—color-infrared: 4, 3, 2
• SPOT Multispectral—color-infrared: 3, 2, 1