Joining attribute data from related tables using QGIS

Our post today will show you how to join the attributes from one table to the attribute table  of a layer on a map using QGIS. To create a join of both tables, an identical field must exist between them, in other words, a relationship must exist between them.

Tables are a very important form of storage in GIS. Attribute (that is descriptive) data on a spatial object are usually kept in tabular form.
Below is our table containing data from the results of a building survey done on these points in the Ibadan municipality. the table is stored in comma seperated values .csv format.

Secondly, let us look below at a registered image of Ibadan municipality where we can clearly see our points (red dots) stored as a layer. All these other attribute data of these points on the table above will need to be joined to the shape file on the map.

Click on the link  Joining tables and follow the steps.

Hope you are practicing already. Feel free to send us your feedback.

QGIS SERIES- MAKING GIS AFFORDABLE?

The QGIS (formerly known as Quantum GIS) platform is an open source GIS platform run by contributors from all over the world. Before the advent of QGIS, similar GiS software packages have been proprietary like MapInfo and Esri ArcGIS. These proprietary packages are expensive and mostly were targeted at corporate users. If the Americans and Europeans mourn about the cost of acquiring these proprietary softwares then we in Nigeria and Africa as a whole are just about at our wits end.

The long term effect of these inaccessibility to affordable GIS software packages has been a software market awash with faulty, half complete, unstable and pirated copies of ArcGIS and Mapinfo. Of course, one should forget the calm group that always managing through on trial versions.

Suffice to say QGIS on the scene  and for free naira is a cool relief. And here comes the catch, we hope to help in making it as popular and useful on the scene as ArcGIS and MapInfo has been for years.

We intend to be posting basic tips on how to use QGIS and the plugins.  QGIS statement is clear, you don’t have to pay so much to become a GIS user. We start this series with a presentation on how to georeference a raster  image with QGIS  using the 2.8 version.why georeferencing? Most times in our clime her, the first thing most people want to know is how to georeference their raster images so as digitize the features into vectors.

QGIS 2.8 is a free application downloadable from the web. Just google ‘download QGIS 2.8′ on your browser.

If you are a user of QGIS, what do you think? we welcome your feedback. Just go to our Feedback page and fill the form.

My Loch Lomond tour in a Story map

Believe me, i really tried to enjoy myself. I am a history buff and the moment i watched and fell in love with the epic-Brave Heart, i packed vacation bags and headed to see some of the real thing. Funny, its was late autumn and the Scottish hale was getting set for full bloom.

well have a peek at my story, albeit a very small peek.

http://arcg.is/1FONtDP

I hope u enjoy this story till i come back with a serious story.

WE GOT THE PAGE FOR YOU!!! DYNAMIC WEB APPLICATION FOR COMPARISON ANALYSIS

In our previous post- ‘Lets Analyze’, we could only supply you all with a static map to do the Comparison analysis on the development of Land Parcels in the cadastral layout.

Due to technical issues, we unable to link with the dynamic web map

We intend to continue next to asking the spatial data about its attributes.

Enjoy the post

For my last posting @Mapping is an activity-indoor and outdoor, I enumerated the various choices we have when performing the activity of mapping spatial objects and non-spatial objects. Principally since our focus is on spatial objects and the environment around us, it is better we break right into how satellite imagery data we acquire from the activity of mapping can become useful to us all.

Our area of study is a Cadastral Layout of Landed parcel that have been allocated for development and the objective is to analyze the data available and illustrate the level of development that has taken place in the Landed parcels between the years 2012 and 2015.

Our Data are two forms- 2015 Google imagery of the Cadastral layout showing the Landed Parcels in different levels of development. For purposes of this study, development is rated as fenced, uncompleted or completed building 2) 2012 Open street Map Imagery of the same area in ArcGIS Online.

What did we do  – We digitized the Land Parcels that had shown a form of development (fenced, uncompleted or completed building) on a Jan 2015 Google Imagery of the layout. Click the link below to see dataset on Google maps engine,

Parcels Developed in Study Location as at Jan 2015)

Secondly we added digitized Land Parcels on the 2012 Open street Maps in ArcGIS Online to produce a feature layer of Land Parcels that had been developed by 2012. 

Next, We upload the vector layer into ArcGIS online.to do a Compare analysis using a Web application. ,

Here is the result, join us to analyze!!!!

       Zoom in to 250% for best view.

The map on the left are Parcels developed by 2012 while the one on the right are Parcels developed by 2015. 

Its now easy to analyze which new parcels have been developed, though due to the static nature of the map, we cannot get more attributes.

Hope you have enjoyed my post as I enumerate how we can also carry out mapping activity using satellite imagery. I know many of you folks will prefer that but watch out for my next post because there might always be need to see things for yourself outdoors,

Your comments are invited 

Basics Theory of Global Positioning Systems Technology (GPS)

Back to the basic – by popular demand

Mapping is any activity carried out with the intent of collecting credible and accurate data on an object e.g. Building, roads, human genome or phenomenon e.g. buying patterns, smuggling and illegal immigration. To go a step further, spatial mapping is when the geographical coordinates of the object or phenomenon is also taken. In other words, the GPS coordinates!!!!

So what are geographic coordinates ooh!!

Geographic coordinates are the X and Y of any object position on the face of the earth pronto!! X stands for the longitude, Y for the Latitude. The X and Y tells us the unique position of an object on the face of the earth.

How do we now get the X and Y coordinates when mapping? Namely on the field and in the laboratory or on the Workstation even your mobile device!!First Choice? Lets take field mapping first

We deploy a technology called Global Positioning System Technology, GPS for short. The technology works through what we know as GPS Enabled devices. These are common now as almost all telecommunication devices, cars, trains even wristwatches are now GPS Enabled!!!

How do we use these devices?

When we use these devices to map a road for example, we use certain functions that exist in the devices. These functions assist us to get a real life representation of how the road looks. Really, a road doesn’t look like a lamp post, neither does it look like a building!!!

Note: not all GPS Enabled devices have Mapping capability but all have the ability to register the basic X and Y of a location. Devices designed with the objective of mapping are usually labelled as so. For example- Handheld GPS devices, Rugged GPS Enabled Notebooks amongst others.

So what does the GPS technology map? The GPS Enabled devices map what we call features. Features are of three main kinds- Points, Area and Lines.

Second Choice: How do we now get the X and Y coordinates when mapping? When one cannot go out? Mapping can also be an indoor activity lol One cannot map human genome in the garden anyway!!! Lol

Today, we are all familiar with dynamic or internet based maps, satellite imagery and aerial photographs. In a GIS Laboratory or Workstation and with the right tools for analysis and interpretation, certain X and Y coordinates of recognizable locations on the earth surface can be extracted. Note that these remotely sensed datasets must be themselves georeferenced.

Even simpler is your handy google maps engine. Here by simply clicking geocoded locations on the face of the earth, their X and Y coordinates can be extracted For example putting in a search for lagos will generate a marker on the google map engine that contains the X and Y coordinates of Lagos!!!!!!

Go to presentation page on menu bar and click links on presentations titled 'GPS Data' and 'Coordinates&Projections'for greater details