1.16. SVG Shadow

Note: Internet Explorer and Safari do not support SVG filters!
1.16.1.
   and     ¶  All SVG filters for the Internet are defined in    element.    element definitions are short and contain special element definitions, such as filters. 
   tags are used to define SVG filters.    the tag usesthe required id attribute to define which filter to apply to the drawing? 
 1.16.2.  SVG     ¶  Example 1  ¶ 
   elements are used to create shadow effects. Our idea is to take a SVG graphic (image or element) and move it a little bit on the xy plane. 
The first example is offset by a rectangle (with    ), and then blend and offset the top of the image (including    ): 
  
 Here is the SVG code:
 Example
 <svg xmlns="http://www.w3.org/2000/svg" version="1.1">
  <defs>
    <filter id="f1" x="0" y="0" width="200%" height="200%">
      <feOffset result="offOut" in="SourceGraphic" dx="20" dy="20" />
      <feBlend in="SourceGraphic" in2="offOut" mode="normal" />
    filter>
  defs>
  <rect width="90" height="90" stroke="green" stroke-width="3"
  fill="yellow" filter="url(#f1)" />
svg>
    Code parsing: 
         the element id attribute defines a unique name for a filter   
       the filter attribute of the element is used to link the element to the “F1” filter     
  Example 2  ¶  
  Now, the offset image can be blurred (including      ):  
    
  Here is the SVG code: 
  Example 
   <svg xmlns="http://www.w3.org/2000/svg" version="1.1">
  <defs>
    <filter id="f1" x="0" y="0" width="200%" height="200%">
      <feOffset result="offOut" in="SourceGraphic" dx="20" dy="20" />
      <feGaussianBlur result="blurOut" in="offOut" stdDeviation="10" />
      <feBlend in="SourceGraphic" in2="blurOut" mode="normal" />
    filter>
  defs>
  <rect width="90" height="90" stroke="green" stroke-width="3"
  fill="yellow" filter="url(#f1)" />
svg>
    Code parsing: 
    The stdDeviation attribute of the < feGaussianBlur > element defines the fuzzy amount 
 
 
    Example 3  ¶  
  Now, make a black shadow: 
   
  Here is the SVG code: 
  Example 
   <svg xmlns="http://www.w3.org/2000/svg" version="1.1">
  <defs>
    <filter id="f1" x="0" y="0" width="200%" height="200%">
      <feOffset result="offOut" in="SourceAlpha" dx="20" dy="20" />
      <feGaussianBlur result="blurOut" in="offOut" stdDeviation="10" />
      <feBlend in="SourceGraphic" in2="blurOut" mode="normal" />
    filter>
  defs>
  <rect width="90" height="90" stroke="green" stroke-width="3"
  fill="yellow" filter="url(#f1)" />
svg>
    Code parsing: 
    The attribute of the < feOffset > element is changed to “SourceAlpha” to use the residual shadow in the Alpha channel instead of the entire RGBA pixel. 
 
 
    Example 4  ¶  
  Now put a layer of color on the shadow: 
   
  Here is the SVG code: 
  Example 
   <svg xmlns="http://www.w3.org/2000/svg" version="1.1">
  <defs>
    <filter id="f1" x="0" y="0" width="200%" height="200%">
      <feOffset result="offOut" in="SourceGraphic" dx="20" dy="20" />
      <feColorMatrix result="matrixOut" in="offOut" type="matrix"
      values="0.2 0 0 0 0 0 0.2 0 0 0 0 0 0.2 0 0 0 0 0 1 0" />
      <feGaussianBlur result="blurOut" in="matrixOut" stdDeviation="10"
/>
      <feBlend in="SourceGraphic" in2="blurOut" mode="normal" />
    filter>
  defs>
  <rect width="90" height="90" stroke="green" stroke-width="3"
  fill="yellow" filter="url(#f1)" />
svg>
    Code parsing: 
         the filter is used to convert the offset image closer tothe black color. All three values of the ‘0.2’ matrix are multiplied by red, green and blue channels. Reduce the color brought by its value to black(black is 0)       
                    
                
                

                    
                        
                            
                                文章链接
                            
                            ：
                            1.16. SVG Shadow 
                        
                    
                

            
        
        
            

    
        
            
                
                    
                        
                        
                            Principles and Applications of WebGIS 
                        
                        
                             37
                        
                    
                    
                        
                            
  
 
                        
                    
                
                
                    
                        
                            
                                
                                    1. Geographical Information Systems in the World Wide Web Era 
                                    
                                        4
                                    
                                
                            
                        
                    
                        
                            
                                
                                    2. Basic technology of WebGIS 
                                    
                                        4
                                    
                                
                            
                        
                    
                        
                            
                                
                                    3. Geographic Web Services 
                                    
                                        5
                                    
                                
                            
                        
                    
                        
                            
                                
                                    4. aggregation of geographical information 
                                    
                                        4
                                    
                                
                            
                        
                    
                        
                            
                                
                                    5. mobile GIS 
                                    
                                        5
                                    
                                
                            
                        
                    
                        
                            
                                
                                    6. Geographic information portal 
                                    
                                        3
                                    
                                
                            
                        
                    
                        
                            
                                
                                    7. New generation national spatial data infrastructure and GIS 
                                    
                                        4
                                    
                                
                            
                        
                    
                        
                            
                                
                                    8. Application of WebGIS in E-Commerce 
                                    
                                        3
                                    
                                
                            
                        
                    
                        
                            
                                
                                    9. Application of WebGIS in E-government 
                                    
                                        3
                                    
                                
                            
                        
                    
                        
                            
                                
                                    10. Hotspots and frontiers of WebGIS 
                                    
                                        2
                                    
                                
                            
                        
                    
                
            
        
    

    
        
            
                
                    
                        
                        
                            Web框架 
                        
                        
                             942
                        
                    
                    
                        
                            
  
 
                        
                    
                
                
                    
                        
                            
                                
                                    1. Angularjs2 
                                    
                                        8
                                    
                                
                            
                        
                    
                        
                            
                                
                                    1. SVG tutorial 
                                    
                                        19
                                    
                                
                            
                        
                    
                        
                            
                                
                                    1. Memcached 
                                    
                                        20
                                    
                                
                            
                        
                    
                        
                            
                                
                                    1. C# tutorial 
                                    
                                        61
                                    
                                
                            
                        
                    
                        
                            
                                
                                    1. Sqlite 
                                    
                                        47
                                    
                                
                            
                        
                    
                        
                            
                                
                                    2. Go 
                                    
                                        43
                                    
                                
                            
                        
                    
                        
                            
                                
                                    2. Docker 
                                    
                                        59
                                    
                                
                            
                        
                    
                        
                            
                                
                                    2. Vue3 
                                    
                                        19
                                    
                                
                            
                        
                    
                        
                            
                                
                                    2. Servlet 
                                    
                                        21
                                    
                                
                            
                        
                    
                        
                            
                                
                                    3. React 
                                    
                                        23
                                    
                                
                            
                        
                    
                        
                            
                                
                                    3. SOAP tutorial 
                                    
                                        10
                                    
                                
                            
                        
                    
                        
                            
                                
                                    3. Android 
                                    
                                        18
                                    
                                
                            
                        
                    
                        
                            
                                
                                    3. Mongodb 
                                    
                                        44
                                    
                                
                            
                        
                    
                        
                            
                                
                                    3. Kotlin 
                                    
                                        18
                                    
                                
                            
                        
                    
                        
                            
                                
                                    4. Lua 
                                    
                                        31
                                    
                                
                            
                        
                    
                        
                            
                                
                                    4. MySQL tutorial 
                                    
                                        34
                                    
                                
                            
                        
                    
                        
                            
                                
                                    4. Appml 
                                    
                                        12
                                    
                                
                            
                        
                    
                        
                            
                                
                                    5. Perl 
                                    
                                        45
                                    
                                
                            
                        
                    
                        
                            
                                
                                    5. Postgresql 
                                    
                                        41
                                    
                                
                            
                        
                    
                        
                            
                                
                                    web 
                                    
                                        15
                                    
                                
                            
                        
                    
                        
                            
                                
                                    5. Web Services tutorial 
                                    
                                        6
                                    
                                
                            
                        
                    
                        
                            
                                
                                    6. Ruby 
                                    
                                        41
                                    
                                
                            
                        
                    
                        
                            
                                
                                    6. Design-pattern 
                                    
                                        35
                                    
                                
                            
                        
                    
                        
                            
                                
                                    7. Django 
                                    
                                        18
                                    
                                
                            
                        
                    
                        
                            
                                
                                    7. Rust 
                                    
                                        22
                                    
                                
                            
                        
                    
                        
                            
                                
                                    6. WSDL tutorial 
                                    
                                        8
                                    
                                
                            
                        
                    
                        
                            
                                
                                    8. Foundation 
                                    
                                        39
                                    
                                
                            
                        
                    
                        
                            
                                
                                    9. Ios 
                                    
                                        43
                                    
                                
                            
                        
                    
                        
                            
                                
                                    8. Css3 
                                    
                                        26
                                    
                                
                            
                        
                    
                        
                            
                                
                                    9. Swift 
                                    
                                        43
                                    
                                
                            
                        
                    
                        
                            
                                
                                    11. HTML tutorial-(HTML5 Standard) 
                                    
                                        54
                                    
                                
                            
                        
                    
                        
                            
                                
                                    12. Http 
                                    
                                        6
                                    
                                
                            
                        
                    
                        
                            
                                
                                    13. Regex 
                                    
                                        6
                                    
                                
                            
                        
                    
                        
                            
                                
                                    14. Regexp 
                                    
                                        7
                                    
                                
                            
                        
                    
                
            
        
    

    
        
            
                
                    
                        
                        
                            WEB基础 
                        
                        
                             287
                        
                    
                    
                        
                            
  
 
                        
                    
                
                
                    
                        
                            
                                
                                    2. ADO tutorial 
                                    
                                        23
                                    
                                
                            
                        
                    
                        
                            
                                
                                    4. W3C tutorial 
                                    
                                        16
                                    
                                
                            
                        
                    
                        
                            
                                
                                    5. Data-structures 
                                    
                                        31
                                    
                                
                            
                        
                    
                        
                            
                                
                                    8. Scala 
                                    
                                        41
                                    
                                
                            
                        
                    
                        
                            
                                
                                    7. Bootstrap5 
                                    
                                        37
                                    
                                
                            
                        
                    
                        
                            
                                
                                    10. Markdown 
                                    
                                        10
                                    
                                
                            
                        
                    
                        
                            
                                
                                    9. Echarts 
                                    
                                        12
                                    
                                
                            
                        
                    
                        
                            
                                
                                    11. Maven 
                                    
                                        20
                                    
                                
                            
                        
                    
                        
                            
                                
                                    10. Font-awesome 
                                    
                                        16
                                    
                                
                            
                        
                    
                        
                            
                                
                                    12. RDF tutorial 
                                    
                                        11
                                    
                                
                            
                        
                    
                        
                            
                                
                                    13. Sass 
                                    
                                        14
                                    
                                
                            
                        
                    
                        
                            
                                
                                    15. XML Schema tutorial 
                                    
                                        56
                                    
                                
                            
                        
                    
                
            
        
    

    
        
            
                
                    
                        
                        
                            Principles, Technologies, and Methods of Geographic Information Systems 
                        
                        
                             102
                        
                    
                    
                        
                            
   In recent years, Geographic Information Systems (GIS) have undergone rapid development in both theoretical and practical dimensions. GIS has been widely applied for modeling and decision-making support across various fields such as urban management, regional planning, and environmental remediation, establishing geographic information as a vital component of the information era. The introduction of the “Digital Earth” concept has further accelerated the advancement of GIS, which serves as its technical foundation. Concurrently, scholars have been dedicated to theoretical research in areas like spatial cognition, spatial data uncertainty, and the formalization of spatial relationships. This reflects the dual nature of GIS as both an applied technology and an academic discipline, with the two aspects forming a mutually reinforcing cycle of progress. 
 
 
                        
                    
                
                
                    
                        
                            
                                
                                    1. Introduction to Geographic Information Systems 
                                    
                                        6
                                    
                                
                            
                        
                    
                        
                            
                                
                                    2. From the Real World to the Bit World 
                                    
                                        3
                                    
                                
                            
                        
                    
                        
                            
                                
                                    3. Spatial Data Model 
                                    
                                        7
                                    
                                
                            
                        
                    
                        
                            
                                
                                    4. Spatial Reference Systems and Map Projections 
                                    
                                        5
                                    
                                
                            
                        
                    
                        
                            
                                
                                    5. Data in GIS 
                                    
                                        4
                                    
                                
                            
                        
                    
                        
                            
                                
                                    6. Spatial data acquisition 
                                    
                                        2
                                    
                                
                            
                        
                    
                        
                            
                                
                                    7. Spatial Data Management 
                                    
                                        6
                                    
                                
                            
                        
                    
                        
                            
                                
                                    8. Spatial analysis 
                                    
                                        8
                                    
                                
                            
                        
                    
                        
                            
                                
                                    9. Digital Terrain Model (DTM) and Terrain Analysis 
                                    
                                        5
                                    
                                
                            
                        
                    
                        
                            
                                
                                    10. Spatial modeling and spatial decision support 
                                    
                                        6
                                    
                                
                            
                        
                    
                        
                            
                                
                                    11. Spatial data representation and map making 
                                    
                                        6
                                    
                                
                            
                        
                    
                        
                            
                                
                                    12. 3S Integration Technology 
                                    
                                        5
                                    
                                
                            
                        
                    
                        
                            
                                
                                    13. Network Geographic Information System 
                                    
                                        4
                                    
                                
                            
                        
                    
                        
                            
                                
                                    14. Examples of Geographic Information System Application 
                                    
                                        8
                                    
                                
                            
                        
                    
                        
                            
                                
                                    15. Organization and Management of Geographic Information System Application Projects 
                                    
                                        10
                                    
                                
                            
                        
                    
                        
                            
                                
                                    16. Geographic Information system Software Engineering Technology 
                                    
                                        7
                                    
                                
                            
                        
                    
                        
                            
                                
                                    17. Geographic Information System Standards 
                                    
                                        3
                                    
                                
                            
                        
                    
                        
                            
                                
                                    18. Geographic Information System and Society 
                                    
                                        3
                                    
                                
                            
                        
                    
                        
                            
                                
                                    19. Earth Information Science and Digital Earth 
                                    
                                        4
                                    
                                
                            
                        
                    
                
            
        
    

    

    

    


            
            
            
            
            
            
            
            
            
            
            
            
            
            
            
            
            
            
            
            
            
            
            
            
            
            
            
            
            
            
            
            
            
            
            
            
            
            
            
            
            
            
            
            
            
            
        
    

                        
                        
                    
                
            
            
                
                    
                        
                            Powered by Django & PostgreSQL (with PostGIS)