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lesson_1 [2013/08/05 19:23]
admin 		lesson_1 [2019/08/13 12:49]
argemiro ↷ Page moved and renamed from tutorial:data_structures_and_formats to lesson_1
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-===== Data structures and formats ​===== +{{ :​logo_guidebook1.jpg?​400 |}} 
- +\\ 
 +=====LESSON 1: Dinamica EGO data structures and file format=====   
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 +\\
  
 ==== What will you learn? ==== ==== What will you learn? ====
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 <note important>​In map algebra, the null concept is very important to obtain an intelligible result from a model execution. Null means absence of data. Thus a map containing an irregular geographic area of interest, which does not completely cover the geographic plane, must contain a representation for null cell. The value reserved for null cell representation may vary depending on the data cell type, i.e. the size in terms of bits used to store the cell values of a map. Dinamica EGO supports data cell types as follows: {{ :​tutorial:​data_cell_types.jpg |}}\\ Usually, the lowest negative value is used to represent the null value. For example -32768 for Signed 16 Bit Integer. Always choose a data cell type able to embrace the range of values contained in a variable. For example: elevation, varying from -10 meters to 4000 meters, must be represented as Signed 16 Bit Integer or IEEE 754 32 Bit Real.</​note>​ <note important>​In map algebra, the null concept is very important to obtain an intelligible result from a model execution. Null means absence of data. Thus a map containing an irregular geographic area of interest, which does not completely cover the geographic plane, must contain a representation for null cell. The value reserved for null cell representation may vary depending on the data cell type, i.e. the size in terms of bits used to store the cell values of a map. Dinamica EGO supports data cell types as follows: {{ :​tutorial:​data_cell_types.jpg |}}\\ Usually, the lowest negative value is used to represent the null value. For example -32768 for Signed 16 Bit Integer. Always choose a data cell type able to embrace the range of values contained in a variable. For example: elevation, varying from -10 meters to 4000 meters, must be represented as Signed 16 Bit Integer or IEEE 754 32 Bit Real.</​note>​
  
-<note warning> You may need (and must) in some cases to define the null value when loading a Geotiff dataset, which lacks this definition (highly advised). Learn in [[tutorial:​building_a_simple_model|Building a simple model Lesson]] how to do this.</​note>​\\+<note warning> You may need (and must) in some cases to define the null value when loading a Geotiff ​and some other dataset, which lacks this definition (highly advised). Learn in [[tutorial:​building_a_simple_model|Building a simple model Lesson]] how to do this.</​note>​\\
  
 Tables are a convenient way to represent attribute data, usually pertaining to a certain geographic zone, for example: country, state or counties. Dinamica EGO can read data in Comma Separated Value format, as follows. Basically, it is possible to use two different kinds of tables: [[:table type|tables]] and [[:lookup table type|lookup tables]]. Tables are a convenient way to represent attribute data, usually pertaining to a certain geographic zone, for example: country, state or counties. Dinamica EGO can read data in Comma Separated Value format, as follows. Basically, it is possible to use two different kinds of tables: [[:table type|tables]] and [[:lookup table type|lookup tables]].