The power of spatial SQL in MapInfo Professional

Peter Horsbøll MøllerSenior Systems Engineer

Pitney Bowes Software

The Power of Spatial SQL in MapInfo Professional

Peter Horsbøll MøllerSenior Systems EngineerJune 15, 2012

Every connection is a new opportunity™

Workshop agenda

• In this workshop we will play around with the spatial SQL capabilties of MapInfo Professional

• We will look at joining tables based on the spatial objects• We will calculate size of parts of the spatial objects• We will extract and insert parts into new tables

3

SQL Select

• Columns, expressions

• Tables• Conditions

4

Joining via the spatial object

• Select the two tables– Object will come from

first table

• Specify spatial condition:– Contains– Within– Intersects– Partly Within– Contains Part– Entirely Within– Contains Entire

5

Contains / Within

• Comparing the Centroid!

• Order does matter• Good with points

• A Contains C• A Contains D• B Contain A• C Contains D

• C Within A• D Within A• B Within A• D Within C

6

Intersects / Partly Within / Contains Part

• Comparing the entire object!

• Order doesn’t matter

• A Contains Part B• A Contains Part C• A Contains Part D• B Contain Part A• B Contains Part C• B Contains Part D• C Contains Part A• C Contains Part B• C Contains Part S• D Contains Part A• D Contains Part C

7

Contains Entire / Entirely Within

• Comparing the entire object!

• Order does matter

• A Contains Entire D• C Contains Entire D

• D Entirely Within A• D Entirely Within C

8

Spatial operators

• Within/Contains– Very fast– Inprecise when working with other objects than points

• Intersects/Partly Within/Contains Part– Slower then Within/Contains– Should be used when comparing lines/polylines and regions

• Entirely Within/Contains Entire– Slower then Within/Contains– To be used if one object should be ”entirely within” the other

9

Specifying columns

• Pick the columns from the ”Columns” list

• Create expressions using the ”Functions” list or type in some functions manually

• Use aliases (”some new name”) for expressions

10

Exercise

• Join the two tables Cadastre and Urban_Area• Join them using the Intersects operator• Select these columns

– CADASTRE.AREA_NAME– CADASTRE.LOT_NO– URBAN_AREAS.NAME

• Add these functions and aliases:– CartesianArea(CADASTRE.OBJ, "sq m") "Area_Cadastre”– CartesianArea(URBAN_AREAS.OBJ, "sq m") "Area_UrbanArea"

11

Adding a overlap tolerance

• Overlap(obj1, obj2):– Creates an object where

the two objects have a common ”area”

• MapInfo Pro will create this object and calculate the area of it

• If this area is larger then 10 sq m, the intersection will be used

12

Calculating area overlap

There are a number of ways to calculate the size of the overlapping area:

• CartesianArea(Overlap(obj, obj), units)– Uses the defined units– Should be used for projected data (non Longitude/Latitude data)

• SpericalArea(Overlap(obj, obj), units)– Uses the defined units– Should be used for Longitude/Latitude data

• AreaOverlap(obj, obj)– Uses the current units in MapInfo Professional– Uses the SpericalArea calculation

13

Exercise

• Add a overlap tolerance by adding this to the condition:– CartesianArea(Overlap(Cadastre.obj, Urban_Areas.obj), "sq m") >

10

• Try different tolerances• How do you change the unit used?

14

Extracting spatial data

• By default MapInfo Professional takes the spatial object from the first table in your query

• You can however add ”more” spatial objects to your query thru the ”Column” field

• To see these extra columns you need to insert the result into a new/another table

15

Adding an extra spatial column

• Add your extra spatial object, can be an expression

• Consider using an alias

• Note that the result still will highlight the entire area from the first table

16

Creating a new table

• You can consider using the structure from your first table and just modify it to match the columns in your query

17

Inserting the query

• You need to do this thru the MapBasic window• Show the MapBasic Window from the Options menu• Write this:

Insert Into OverlapResult (AREA_NAME, LOT_NO, NAME, OBJ) Select AREA_NAME, LOT_NO, NAME, OverlapObj From Query1

• Where– OverlapResult is your new table– OverlapObj is your spatial column alias– Query1 is the name of yoru query

• And hit enter• Make sure your new table hasn’t been added to the map

as that will slow it down – a lot!18

Final result

19

Exercise

• Add a spatial column to your result• Create a new table• Insert the result into this new table using this:Insert Into OverlapResult (AREA_NAME, LOT_NO, NAME, OBJ) Select AREA_NAME, LOT_NO, NAME, OverlapObj From Query3

20

Regions and lines/polylines

• Works just like regions and regions

• Note that Overlap uses the style from the first object

21

Exercise

• Find the roads that intersects the urban areas• Use these columns from the roads:

– ROADNAME– ROUTE_NO– ID

• And this column from the urban areas– NAME

• Extract only the part of the road within the urban area• Create a new table• Insert the result into this new table

Insert Into UrbanRoads (ROADNAME,ROUTE_NO,ID,NAME, OBJ) Select ROADNAME,ROUTE_NO,ID,NAME, LineOverlap From Query1

22

Adding multiple spatial columns

• The SQL statement can include several spatial columns

23

Select Cadastre.LOT_NO , Cadastre.AREA_NAME , Cadastre.obj "CObj" , Urban_Areas.obj "UObj" , Overlap(Cadastre.obj , Urban_Areas.obj) "JOBJ" From Cadastre, Urban_Areas Where Cadastre.Obj Intersects Urban_Areas.Obj into Selection

Extracting multiple spatial objects

• You need MapBasic to get to these ”many” spatial columns

• They could be inserted into the cosmetic layer in this way:

Fetch First From SelectionDim oTemp As ObjectoTemp = selection.UObjInsert Into WindowInfo(FrontWindow(), 10) (OBJ) Values (oTemp)

24

Exercise

• Select multiple spatial columns• Insert a few of the selected spatial data into the cosmetic

layer of a map window

25

Some other spatial function

• Overlap()• Erase()• Combine()

• IntersectNodes()• ExtractNodes()

• MBR()• Centroid()

• CreatePoint()• CreateLine()• Buffer() (Cart/Sper)• Offset() (Cart/Sper)• OffsetXY() (Cart/Sper)• Rotate()• RotateAtPoint()

26

Thank You

Peter Horsbøll Møller

peter.moller@pb.com