Mapserver Intro

8/2/2019 Mapserver Intro

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GIS and the Internet

Getting started with the

UMN MapServer


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MapServer Origins

Developed at UMN Remote Sensing Lab

Funded by NASA Mission to Planet Earth

Started as Arc/Info AML generation script

Built on top of standard OpenSource

projects like GD, Flex, Bison, FreeType,

Proj.4 and libTIFF


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System Characteristics

OpenSource software

Implemented as a CGI program

Written in ANSI C/C++

Source distribution

UNIX: autoconf and automake

95/98/NT: VC++ makefiles


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Basic Functionality

Map creation

Map component (eg. legend, scalebar and

reference map) automation

Web application building

Simple feature query

Basic Demonstration Application
http://maps.dnr.state.mn.us/mapserver_demos/workshop/http://maps.dnr.state.mn.us/mapserver_demos/workshop/


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Advanced Functionality ...

On-the-fly projection (w/Proj.4)

Feature annotation including scaling,

rotation, outlines and drop shadows

TrueType labels and symbols (w/FreeType)

Feature classification- string comparision,

regex and logical expressions

Scale dependent display and query


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Advanced Functionality...

Query by point, area or feature across

multiple layers

Quad-tree spatial indexing for shapefiles

Support for tiled datasets (raster or vector)

Label collision removal

URL based configuration


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Advanced Functionality

OpenGIS specification support for WMS,

Context and WFS (partial)

Programmatic access to underlying C API-

MapScript (available for Perl, Python,

Tk/Tcl, PHP and Java)

24-bit output support, including GDAL-based output (e.g. GeoTIFF)


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Supported File Formats

Vector Formats

ESRI Shapefiles and SDE layers

Inline vector features

Database sources- SDE, Oracle Spatial, PostGIS

Raster Formats (8-bit only)

TIFF*/GeoTIFF

EPPL7

WMS

Numerous additional formats via GDAL/OGR

* indicates files that must be accompanied by an ESRI world file for georeferencing
http://www.remotesensing.org/gdal/http://www.remotesensing.org/gdal/


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MapServer Output Formats

varies based upon software build configuration

image formats include GIF, PNG (8/24 bit),

JPEG, WBMP, and GDAL vector formats include GML (via WMS/WFS

or templates), PDF, SWF (Flash) and SVG

(via templates) templates can be any text-based format

(default is HTML)


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So, how does it work?

Each application is configured using a textfile called a map file

A user adds to the configuration using anHTML form (e.g. layers, area of interest)

Program results are run through a series oftemplates depending on the application (e.g.data browse, feature query)

And the process begins again


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How MapServer Works

web server

MapServer CGI

HTTP

spatialdata

configfiles

templatefiles

HTTP

MapServer application


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How MapServer Works

MapServer CGI

request (HTTP)

response (HTTP)

configfiles

augment config with userinput via request (e.g.what layers and where)

spatialdata

create map componentsand/or execute a query,

write components totemporary web space

templatefiles


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System Installation

Build from source

Install mapserv(.exe) in CGI directory

Create writable (by the user the web server

runs as) temporary image store

build your application


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Typical Application Layout

test (whole application stored in one place)test.map file graphics (images used in application) symbols (symbol files and icons) fonts (font files and index list) data (GIS data)*.html (supporting HTML and templates)

Map file is referred to using its full path relative to the

location of the MapServer CGI binary.


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MapServer Map Files

Text based, hierarchical

Control all aspects of an application

legends, scalebars, reference mapslayer definitions

web template definitions

simple one layer example
http://terrasip.gis.umn.edu/projects/tutorial/example1-1.htmlhttp://terrasip.gis.umn.edu/projects/tutorial/example1-1.html


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Map File Caveats

Case insensitive (with few exceptions)

Paths for files are given relative to the map

file location

Strings must start with a letter and can

contain a-z, A-Z, 0-9, - and _. All other

strings must be quoted.

Order of layers is significant - FIFO.


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Map Object

MAP

NAME application name

STATUS ON|OFFIMAGECOLOR r g b

UNITS METERS|FEET|INCHES|

FONTSET filename

SYMBOLSET filename

SIZE x y

Layers, Scalebar, Legend

END


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Basic Class Object

CLASS

NAME full name for legend

EXPRESSION string

STYLE parameters END

LABEL parameters END

TEXT string

END


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Basic Style Object

STYLE

ANTIALIAS TRUE|FALSE

BACKGROUNDCOLOR r g b

COLOR r g b

OFFSET dx dy

OUTLINECOLOR r g b

SIZE n

SYMBOL n|nameEND


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Basic Label Object

LABEL

TYPE BITMAP|TRUETYPE

FONT name

COLOR r g bOUTLINECOLOR r g b

SIZE n|TINY|SMALL|MEDIUM|LARGE|GIANT

POSITION UL|CC|LR||AUTO

ANGLE n|AUTOBUFFER n

ANTIALIAS TRUE|FALSE

END


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Legend Object

LEGEND

STATUS ON|OFF

KEYSIZE x y

KEYSPACING x y


IMAGECOLOR r g b

END


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Reference Map Object

REFERENCE

STATUS ON|OFF

SIZE x y

EXTENT minx miny maxx maxy

COLOR r g b

OUTLINECOLOR r g b

IMAGE filename

END


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In a nut shell

This is controlled bythe LAYER objects(and sub-objects),and a few MAP levelparameters like SIZEand EXTENT.

These are controlled bythe SCALEBAR objectand its LABEL object.

Controlled by theREFERENCE object.This is a template

AFTER it has beenprocessed byMapServer andreturned to the users

browser.


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Class Object Expressions

Used to group features according to

attribute table values

Each layer can have multiple classes eachwith its own expression

3 expression types supported: string, regex

and logical (can mix and match)

Order of classes is significant


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String Expressions

Fastest to evaluate, based on pure equality

Denote using quotes

Case sensitive

Attribute identified using CLASSITEM

Examples: EXPRESSION ForestEXPRESSION 10


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Regular Expressions

Fairly quick, advanced pattern matching

Most useful with character data

Denote using forward slashes

Attribute identified using CLASSITEM

Examples: EXPRESSION /[Ff]orest/EXPRESSION /hardwood|conifer/

EXPRESSION /2{2}/

EXPRESSION /./


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Logical Expressions...

Slowest, but most flexible

SQLlike syntax, can use multiple attributes

Logical operators: eq, gt, lt, le, ge, ne, and, or

Math operators: +, -, /, * and ^

Grouping using ()s

Strings must be qouted

Denote using ()s


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[ ]s must be used to delineate attributes,

this is case sensitive

Use of CLASSITEM not required

...Logical Expressions

Examples:

EXPRESSION ([AREA] > 10000)

EXPRESSION ([AREA]/[PERIMETER] ge .5)

EXPRESSION ([NAME] eq St. Paul or [ID] != 10)

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Mapserver Intro

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