[Mori city] random talk on GIS data (I)

Recently, a little partner raised some questions about GIS Data problems ：

problem 1： Can the water system map be uploaded to Sen map for use ？ At present, the format types supported by the exported water system map are ：xml、cpg、shx、shp、sbx、prj、sbn、dbf.

problem 2： I made orthophoto images of my modeling area , Can it be imported into the map as part of the tile ？

The above questions are related to GIS Data related issues , To solve these problems, we first need to understand what is GIS？GIS What is the difference between data formats ？

What is? GIS？

Geographic Information System （Geographic Information System or Geo－Information system,GIS） Sometimes called “ Geoscience information system ”. It is a special and very important spatial information system . It's hard in the computer 、 With the support of software system , To the whole or part of the earth's surface （ Including the atmosphere ） Collect the relevant geographic distribution data in space 、 Store 、 management 、 operation 、 analysis 、 Display and description of the technical system .

Modern human behavior and position are closely related , Whether it's sending and receiving express or catering takeout, it's inseparable from location information .GIS It's a comprehensive subject , Combining Geography with cartography, remote sensing and Computer Science , Widely used in different fields . Help us make better use of spatial data to combine with other industry technologies , Carry out powerful auxiliary decision-making and management applications .

Vector data and grid data

GIS There are many ways to classify data , One of the most basic classification methods is also the data structure that we often come into contact with （ Or data model ） You can put GIS Data is divided into vector data and grid data .

vector data

Definition ：  With x、y Space points represented by coordinates or coordinate strings 、 Line 、 The general name of graphic data such as faces and related attribute data .

describe ：  For point entities , The vector structure only records its coordinates and attribute codes in a specific coordinate system ; For line entities , It is represented by the line of a series of coordinate pairs ; For face entities , That's polygons , Express the line with a series of closed coordinates . Vector mode is helpful to describe some discrete features , But for the characteristics of continuous change , For example, soil 、 terrain 、 Mines, etc. are not applicable .

raster data

Definition ：  Grid data structure is the use of regular grids to divide geographical space , Form geographical cover . Each spatial object is mapped to the corresponding geographical grid according to its geographical location , The identification or type of spatial objects contained in each grid record .

describe ：  Grid structure is the simplest and most direct spatial data structure , It uses regular arrays to represent the data organization of spatial feature or phenomenon distribution , Each data in the organization represents the non geometric attributes of a feature or phenomenon . In raster data , Points are represented by a grid cell ; The line is marked by a group of adjacent grid cells along the line , Each grid cell has at most two adjacent cells on the line ; The surface is represented by a set of adjacent grid cells with regional attributes , Each grid cell can have more than two adjacent cells belonging to the same area .

vector 、 Grid data file

Vector data file

The main common data formats of vector data files are ：ShapeFile、GeoJSON、TopoJSON、WKB/WKT（Well-known text）、KML/KMZ. Among them, the most common in actual projects GIS The format of vector data file is ShapeFile and GeoJSON.

ShapeFile

ShapeFile（ Also abbreviated as shp） Is a collection of files , As shown in the figure below, the railway line data is composed of many files with different suffixes . The advantage is good compatibility 、 Widely applied , But from data sharing 、 From the perspective of transmission, it can not meet the needs of network transmission of shared data in the Internet era , That's why later GeoJSON File format .

GeoJSON

GeoJSON Yes, it is JSON Syntax for expressing and storing geographic data , about Web applications ,GeoJSON It is the most widely used data format .GeoJSON The following geometry types are supported ： spot 、 Line 、 Noodles 、 Multipoint 、 Multi line 、 Polyhedra and geometric sets .

It can be seen that ,GeoJSON It is used in 、 Line 、 Face to represent geographical objects , And spatial data （ Or geometric fields ）Geometry There are corresponding points stored in 、 Line 、 Face coordinates . This is the characteristic of vector data , Ready to use 、 Line 、 Surface to represent the geometric characteristics of geographical objects .

problem 1 The solution is ： Sen city supports GeoJSON Data upload , So just put Shapefile The file is converted to GeoJSON After uploading the file to Mori City, you can use .

Grid data file

For all of you , common GIS Grid data is remote sensing image （ Satellite imagery / Satellite photos ）, More broadly, various aerial images （ Photo ） It's all raster data .GIS Data or spatial analysis of some remote sensing applications 、 The calculation result data will generally be provided in the form of grid data , The size of raster data is directly proportional to the spatial range and resolution of the data . Simply put, the larger the scope , The higher the resolution , The larger the amount of data .

So generally, these data will not be uploaded directly to Web End treatment , But the use of GIS Software or other tools make data into map tiles （ section ） Then it will be published as a map service , Re supply Web Front end application display .

The solution to problem two is ： Make orthophoto into map tiles （ section ） After publishing as a map service , Then configure the map tile service address to use .

Tool recommendation

Mori City ： One click generation 3D City , Built in multiple templates , Free editing

• Mori city currently provides nationwide 110 Construction services of standard 3D scenes in multiple cities , Make the construction speed of urban 3D scene increase to minute level .

• Sen city supports the insertion and automatic fusion of different types of city data , And provide friendly and powerful scene editing ability and performance processing ability , Not required GIS、 Modeling and other professional skills , It's easy DIY Own cool 3D city scene .

• Mori city has the ability to output open urban scenes , There is no need to worry about the compatibility of subsequent use of the scene .