Geographic Information System is a system intends to capture, Store, manage, manipulate, analyze the data. GIS system integrate data and convert it into maps. And as we know visuals are more powerful than words so it makes our understanding of data fast.
What is GIS ?
GIS is a tool to acquire geographic data and produce Geographic information. And generally those information are stored in tabular form. GIS can be defined as a “computer information system that can input, store, manipulate, analyze, and display geographically referenced (spatial) data to support decision making processes”.
Simply GIS visualize your data as a map. And these visualization makes the study interesting with interactive maps. It saves the time and make the system decisiveness that is main requirement.
If we want to find out nearby hotels, coffee shop etc on google maps we can find it easily by just right clicking on the selected location and go for search nearby option. The map will show all the nearby selected hotels, coffee shop etc. I wonder how can I do this on a leaflet map with myself. In quest of this question I found Isodistance and Isochrone map APIs.
What are Isodistance and Isochrone maps?
Isodistance maps:
An isodistance map is a map showing equal distance polygons from a point of interest considering every possible route. For example you decide to go for a morning walk daily for about 1 mile and you want to find out all the possible routes from your house on which you can walk ½ mile and then come back ½ mile, isodistance map is your solution.
As stated in Mapbox – “Isodistances offer realistic travel distances by considering roads and sidewalks, which can be the difference between a day at the beach and waiting for a tow truck.”
isodistance-mapbox
Isochrone maps:
halifax-map-isochrone
Isochrone maps are similar to isodistance map but here we consider time. An isochrone map is map which shows lines of equal travel time across a geographic area. As in the below snapshot example if you decide to walk 8 mins daily then you can find how much distance you might cover from your house in 8 mins.
APIs for Isodistance and Isochrone maps:
There are two APIs available for creating Isodistance maps. One is MapBox Directions API and another is ISO4APP API. This two APIs can be used with leaflet or google map. For Isochrone maps there is one API available that is ISO4APP API.
What you think about isodistance and isochrone maps? In which situtation are you using this algorithm? Do you know any other api which i have not listed? Do share your answer by commenting below in the area provided.
Flight Routes Network Analysis. When we think of Network analysis in GIS we think of roads, rivers, waterlines etc. In GIS two types of network are modeled. i.e:
1.)Transportation Networkfor example road networksand
2.) Utility Network for example gas pipeline network.
In transportation network model analysing air transportation network is afascinating network visualisation exercise.
FLIGHT ROUTES NETWORK ANALYSIS
Force-directed graph drawing algorithms are a class of algorithms for drawing graphs in an aesthetically pleasing way. This algorithm used by Martin Grandjean a researcher from The University of Lausanne, Switzerland to analyze the air transportation network created by 100,000 airline flights that take place around the world. Data for this analysis of the 3,275 airports across the globe was taken from openFlights.org.
A map showing flight routesbetween these airports is a network graph. Martin Grandjean attempts to make explicit the network behind air transport. The structure of the relationships has an impact on the spatial distribution of nodes in a graph. Let’s see how this landscape is reorganized without geographical constraints.
FLIGHT ROUTES NETWORK ANALYSIS
Explanation of the above image: “Naturally, network geography is not completely disrupted: the continents are mostly visible and regions are generally in their original position (with the exception of the Pacific islands that connect Asia and America – imagine this graph in three dimensions, with the Pacific Ocean behind). Major observations: India is more connected to the Middle East than to South and East Asia. The Russian cluster is very visible, connecting airports in Russia but also in many former Soviet republics. Latin america is clearly divided between a South cluster and a Central American cluster very connected with the U.S.”
I found this information very fascinating, to know the way for Flight Routes Network Analysis.
Google Map a giant, smooth and one of the fastest map is touching every part of your life by helping you find any location by just clicking on single search button. And now Google Map is looking to redesign its mobile experience of google Map by showing some relevant ads tagged as Google Map advertisement.
What are the Expected Type of Google Map advertisement:
So what kind of ads would be shown on Google Map? Either as a purple pin on the map or as a logo would appear at its exact physical location on digital map, within the visible map area or near by you location. You can see an examples purple pin ad of ‘Walgreens’ as shown in the image provided below.
Google Map advertisement
Along with pin ads Google map will also feature in-store promotions i.e when you expand a business page. Where you can see also see deals and coupon for sale items along with store hours and address. A small purple box with the word ‘Ad’ will highlight ad placements.
Google Map advertisement would appear in a subtle manner:
When will the ads will be shown? While the relevancy of ads would be better applied when you are using the app and searching for some kind of location. For example if you search for a nearby hotels, Google Map can show a purple promoted pin or its company logo which will be more attractive than any other.
Also while you are driving and using google Navigation function, a purple pin may appear sometimes, which locates nearby restaurant or gas station. This ads may be definitely be useful sometimes as people or driver would get aware of the location of some place of a route. As Google takes care of user experience so you don’t need to worry if ads might distract the drivers attention from the navigation route shown.
Final words
Obviously Google this effort is to make more money, i.e as ads will be shown to users where they receive more than a billion visit on a Google Map.
Although according to Google their first priority is to make sure the advertisement should be useful to users. Also for now, voice direction won’t have any audio advertisement, so that’s a good news while the bad part is that user would not be able to turn off the promoted pins.
Have you seen any Google Map ads till now? If so, please share your experience by commenting here below.
Merge two or more polygons, points or polyline of Shapefile in QGIS. Do you want to merge features of to combine them into one feature and to maintain its database dbf values along with it. QGIS – Quantum Geographic information system is of the most important for geographers and with the help of this tool I would demonstrate you to merge features within same layer. You can also have a look on how to merge more than two shapefiles.
If you haven’t installed QGIS, lets install Latest Quantum GIS first and open it up. Here are the steps to merge features of shapefile in QGIS.
Merge two or more polygons, points or polyline of Shapefile in QGIS:
We can merge two features in Shapefile in QGIS easily. Let’s say I have a Shapefile states.shp and I want to merge two states. Open up your QGIS tool.
1.) Select the layer and click the toggle edit button from the toolbar.
2.) Click on select tool from toolbar as indicated in the image.
Merge two or more polygons, points or polyline of Shapefile
3.) Press control (ctrl) key and click on the features you want to merge to select them.
4.) Click on the Edit option where you can find find merge selected features.
Merge two or more polygons, points or polyline of Shapefile
5.) You will see this window after selecting merge selected button.
6.) In the above dialogue box you can see there are three columns and four rows. In the first row you can select options for the fields so that what value you want to assign for the merged feature. Go ahead and try the given options.
7.) In the last row you can see the option you selected or you can delete that value by simply double clicking on the field and press delete from keyboard. After you are done you can click ok.
8.) You can see the features are merged. you can also check attribute table.
9.) click on save layer edits buttons and then click on toggle editing button if you are done.
Merge two or more polygons, points or polyline of Shapefile
That is all about merging two features of shapefile whether it is polygon, polyline or point features. If you are getting any problem in performing the above steps, do comment below, we would try to solve the problem by discussing over here.
Routing and displaying direction on Map along with showing the instruction for navigation, physical distance, traffic etc is one of the important part of GIS (Geographical Information System), when working on Travel or tourism or logistic projects. Are you Looking for the best Map direction API to create Routes on Web map or map on App? Researching for best performance and list of alternatives routing libraries? There are dozens of Routing API which is either available as premium API, Free till a limit or a completely free Routing API.
Here you will find all the list of Map Routing libraries which I have gone through and researched while working on one of my project. Let me start listing first few free and open source direction Map API followed with API which is available for free till a particular hits limits.
Map Direction API
You may also look over 8 Best Map Engine Alternative to Google Map Engine API.
Top 10 Map Direction API – Routing Libraries
1.) Open Source Routing Machine:
OSRM computes shortest path in a graph and was designed to run well with map data from OSM project.
Can either be self hosted
Very fast routing.
Method of contraction hierarchies to compute shortest path routing, in contrast to A* which makes it very fast.
You can compare further maps from OpenStreetMap data routing section from here to get the detailed comparision of above listed API.
Premium Routing Libraries:
5.) Google Map Direction API:
We don’t need any introduction to Google Maps. Map with most data provides all roads in every mode whether it is for car, heavy vehicles, rails, bicycle or pedestrian. You just need to grab a key and use the API to get the directions.
Can access upto 2,500 free direction request per day.
Can add upto 23 waypoints
Can avoid route with tolls, highways, ferries and indoor.
Different languages are supported as an output result
Get the documentation link from here and get started with Google Map library.
6.) Bing Map Direction API :
Bing Map is another giant map service provider. You may look as an alternative of Google Map. You can customize, calculate and display direction and route on a Map with Direction API module or with Bing Map Rest Services. You need to get a Map key by registering in Bing Map. I didn’t found any figures of transaction which can be made free. But definitely if you over use the API either Microsoft will contact you or you may contact them either to upgrade the account as Enterprise.
Here are some features of Bing Map:
Calculate Route and get the walking, driving or transit route direction
Define way points
Get Road Shield images
Get Route data i.e Travel Distance, travel duration, estimated time of duration considering live traffic etc.
Turn by turn navigation instruction can be extracted.
You may also look at warning type i.e if there is a traffic accident, very slow traffic in the route, critical weather etc.
You can find the detailed document of the from here:
Bing Map Direction API
7.) ESRI Map Direction API:
ESRI is an international supplier of GIS software and databases and exist since 1969. ESRI Map provides AcrGIS API for JavaScript which helps you to get the Direction on Map. Register a developer account for free in ESRI direction and Routing Service website and get ready to use the library. You will get free development and testing subscription and also gets a 50 credits a month when you are ready to go to production. Yes they charge you according to credits, where each functionality have different credits for different number of hits. Here are some of the features:
Routes for pedestrian, light weight moving vehicle and heavy weight moving vehicle
Get optimized route considering traffic.
“Schedule stops, including people, pickups, work orders, and anything else, within a pre-defined time window.”
According to vehicle weight and height route will be calculated to clear restricted bridges and underpasses.
MapQuest Map provides Direction API with help of OpenStreetMap data. Upto 15,000/month Transactions is allowed for free. Here are the feature of MapQuest :
Get routes for different modes like pedestrian, bicycle, multi-modal.
Routes can be calculated as both fastest and shortest.
Instruction turn by turn navigation.
Get Estimated time of duration for a Route considering real time traffic.
Get Alternate routes for same origin and destination points.
According to date and time, optimized routes will be created.
You can have a look more over here of its documentation.
9.) MapBox Direction Map API:
MapBox is another popular API which can be considered as the best in terms of pricing and performance too. Here are the list of features:
Calculate optimal driving, walking and cycling routes.
Get turn by turn direction instructions.
Route can be created incorporating upto 25 waypoints anywhere on earth.
Get the geometry as a geojson file
Is free till 50,000 mapview either for mobile or for web
Take either shapefile or OSM data. Create R tree and generate the network graph. Implement A* or any shortest path alogrithm. Fix all issues and improve the speed. You are done.
Note: The limitation and features of API is listed on 12-01-2016 and can be changed time to time. So please check the actual price from the concerned API official website. Also features listed of each API is not complete, but just to give you introduction of the same.
The above list I found to be useful and you can choose one by comparing prices and features to implement in your project. Certainly there may be other routing API’s too, which you may not found here. But if you like the same and think that it should be present in the list, then do comment below with the name and some brief description of the map routing library.
Are you running short of fuel at unknown place, while traveling form A to B? Wanted to track Near By Gas Station when there is no one to ask? Well, Google cares about your problem and so, they rolled out Android and iOS Google Map app update to locate Near By Gas Station along with other nearby search point of interest location.
Track Near by gas station and price on Google Map App
The only requirement to search for Gas Station is to have Google Map app in your device and a internet connection or if you have an offline area saved, then their is no need to have an internet connection too. Just grab your mobile open up Google Map and type “Gas Station” in the search box provided, which results out the near by Gas Station to you on the Map with red indicators as seen below. You can also increase the search area by providing the city name followed by ‘gas station’ keyword for example ‘San Francisco gas stations’.
Not only this, but Google Map would also try to help you in providing current rate of Different Gas Station in real time, which will definitely helps you to save some bucks comparing prices and lets you decide where you should fill your vehicle tank.
If you are in navigating mode, then the user can tap on a search icon, then select the gas stations from the drop down menu list which also includes coffee shops, restaurants and grocery stores as indicated by official blog for Google Maps.
Google Map track Near By Gas Station and Current Prices – Android and iOS Appne
This feature will really helps in real time while on a trip, in finding Gas stations when you notice your vehicle gas tank indicating nearing empty. What you think about this Google Map Features? Are you travelling regularly and finding the way to find near by Gas Stations? Is this feature helpful for you? Do share your valuable thoughts by commenting below in the space provided.
Sharing location is pretty easy in Google Maps, while Google also provided a method to directly send a location from Google Map Desktop user to the Android Mobile or iOS mobile device of Same user with pressing just one click on “SEND TO YOUR PHONE” option. Many times you might have searched the location or route on Desktop when planning for travel and then switch back to look on your mobile device while actually travelling.
The place latitude longitude along with name will be received as a notification which directly open up in the Google map pointing to that location. Lets explore sending location form Desktop Google Map to Mobile App Google Map.
Steps to Send Location from Laptop or Desktop Google Map to Android or iOS Google Map App:
1.) Open Google Map in Browser. Check whether the Google Map is not in Lite Mode, or otherwise switch back to full mode from Lite, as the option will not be available in Lite Mode.
2.) Sign in to the Map with your Gmail ID and Search the location which you want to send to yourself.
3.) You can find the details of the location with options to Save the location, find nearby point of interest, send and share. Select “Send to Your mobile” option and select one of your Android or iOS listed phone to which you want to send the notification, with which your Gmail Account is associated.
4.) Once Selected, Google Map will send the location notification to your device without any delay.
5.) As you click on notification info, it will directly open up Google Map, pointing to the location which you have send.
Getting problem, Lets troubleshoot it to Send Place location to Google Map App:
a.) Either your Android device or iPhone Device should be signed with the same Google Account, with which you are trying from Google Map browser. b.) May be your mobile device internet is not working, test it. c.) If you are using iPhone or iPad, follow this steps to give notification permission:
i.) Go to device setting and touch notification. ii.) Scroll to Google Maps and switch on Allow notification.
You may also find send location to device from Apple Map, which may send the location data to Apple iPhone or iPad mobile device.
What you think about the Google Map Send to Your Phone option. How many times you have used this features? Are you getting problem in following above steps? Do comment below to share your thoughts.
Download Save Offline Google Map on app. Map helps you to navigate and find the nearest point of Interest locationwhen you are travelling and at unknown place. While Network service provider doesn’t guarantee you to provide full Network at each and every places you visit, which results in either no or slow internet. Keeping that in mind Google rolled out Offline Map to their user, by letting them to save and download a part of area into their device. This will not only solve the above stated problem but would surely going to help you save mobile data.
Google updated this feature in Mid 2015 for Android Application and in December 2015 for iOS application, which lets users to see live map offline. You may also see now the near by Gas station on Map. Both Search and direction Navigation feature would be supported even after having no internet connection if the Location Map area is downloaded. Below are the steps to know how to download offline Google Map in Android and iOS user.
You may also be interested to see following Google Map tips:
2.) If not signed in, then log in to the application. Click on mobile navigation button, to open up side bar.
3.) Check Offline area in the slidder. If offline Area option is not found, then click on Your Places and scroll down to bottom where it says to download the map area.
Download Save Offline Google Map
4.) Choose the area and click on download button to save the viewable area of Map. Enter the name of the Offline Map.
Note: You cannot select too large area. If you are attempting to do so, then app will ask you to further zoom in to reduce the area.
5.) Let download to get finished. You can see your offline map at “Your Places” option or at “Offline Area” option.
Once downloaded, you can view the saved area of map without internet connection.
Download Save Offline Google Map – Some Important points to keep in Mind
Following are some conditions which you need to keep in mind while downloading and using Google Map offline:
The biggest size which can be downloaded for an offline area is 120,000 square kilometer. This area is more than enough to acquire a single city.
Downloading offline area may not be available in some area or region due to some limitation as per Google.
Data downloaded will be expired after 30 days
Offline area is free to download, but your mobile data charges will apply.
You would get the options to rename, update or delete the offline Map saved, at “Your location” or “Offline Area” Panel. What you think about this Offline Google Map feature? Do comment below with your views.
Image Classification in QGIS: Image classification is one of the most important tasks in image processing and analysis. It is used to analyze land use and land cover classes. With the help of remote sensing we get satellite images such as landsat satellite images. But these images are not enough to analyze, we need to do some processing on them. So to use these images for analysis we need image classification. In this post we will see how to download a Landsat satellite image and image classification in QGIS.
There are many software tools available for image classification such as ArcGIS, ERDAS IMAGIN, but these are not open source software. QGIS(Quantum GIS) is very powerful and useful open source software for image classification. QGIS 3.2.1 for beginners
The basic requirement for image classification is image itself but the other important thing is knowledge of the region for which we are going to classify the image. For this either you need to do manual survey or else you can use google earth. Definitely Manual survey leads to better result.
There are two types of image classification methods..
Supervised classification
Unsupervised classification
Unsupervised classification is not preferred because results are completely based on software’s knowledge of recognizing the pixel. For unsupervised classification you can use KMeansclassification. In this post we will see Supervised classification only.
Download the Sample Image data for classification
Let us see how to download a satellite image first to take out sample image. One of the source is Earth Explorer and register. If you already have an account then sign in.
Note: Please read terms and condition and usages of data.
Here you will see search criteria tab on your left hand side, select it. Enter date and month in the options provided, so that if you want to download image for specific season we can get that image. In rainy season cloud cover is more so it is recommended that we download a image free from cloud cover and mostly of summer of winter season to yield good results.
After zooming in to the location of interest on map click on data sets. And then search for landsat archive. Expand landsat archive option. Depending on our criteria of image we can select more than one option here. We can also set additional criteria based on our requirement.
After setting the criteria click on results. It may take some time to get the results.
Image classification in QGIS
Now analyze the results available on your screen. There are some options given for our convenience. Click on show browse overlay and check if your location comes within the image or not. An image on your screen will appear. It will take some time to display depending on your internet speed as shown below in image.
When you find image of your choice click on download button. Click on the download button of the file which have largest size. Don’t download other data. The download file in the folder is with extension .tar. extract that file and you will get a folder containing all the images and a text document.
Image classification in QGIS
You can see there are 12 images and one MTL text document. This text file is very necessary if this file is not downloaded then image classification will not be possible. We need only 7 images B1 to B7 for image classification, however we can use all the images but it will be very bulky for QGIS to handle and as you start image classification you will understand why we have used 7 images only. You may also consider to look more tutorial on QGIS.
Image Classification in QGIS :
1.) Now open QGIS and install SEMI AUTOMATIC CLASSIFICATION plug-in from the plugin option. After installation of the plugin if toolbox on the screen of the same is not showing by default then, then click view and click panels. And Check both the panels SCP: ROI creation and SCP: classification.
2.) Now click toolbar and activate SCP toolbar.
3.) Your Desktop QGIS screen will look like this below image.
Image classification in QGIS
4.) Now Click on pre-processing tool and Select the folder in which all the images and MTL file is present.
5.) Check these two options i.e Apply DOS1 Atmospheric Correction and Create Virtual Raster as shown below.
6.) Now click on perform conversion. The processing may take too much time. Be patient
Image classification in QGIS
7.) All the images are loaded into Layers and virtual raster with name landsat.vrt is also created.
8.) We can remove image 8,9, 10 and 11. Click on band set icon and select all raster.
9.) Add rasters to band set.
10.) Select landsat 8 only because we have downloaded a landsat 8 image.
11.) Observe the changes in center wavelength.
Image classification in QGIS
12.) Click close. Now Right click on landsat virtual raster and click properties.
13.) Switch to style tab.
14.) Change the band set as shown in the image.
15.) Click apply and observe the changes in the image.
Image classification in QGIS
16.) You can set band set as per your convenience. Set the band set such that you can easily identify land cover and land use classes. For this example we are selecting the above band set. You may also set band set by zooming into your desired location and then load current value of canvas and then click apply. We can do this until we get proper colour for our image.
17.) Now in SCP: ROI creation panel click on new shp. ROI means Region of Interest.
18.) Create a shape file in the same folder with name roi or as per your wish. Click on ‘+’ sign and then Click on create a ROI.
19.) Now as per your knowledge of the location zoom in and create a polygon. We are creating polygon because it will take pixels of same colour with slightly difference in the value. Right click to end the polygon.
Image classification in QGIS
20.) Give Macroclass name and class name.
21.) Click on save ROI and check add sigg. List.
22.) The roi is added to the signature list.
23.) Save this signature list in the same folder, and create new ROI’s for different classes. You can also change the color. Within same class you can have different Macroclass so that you can classify precisely. You can see the color convention for classes that are used generally on internet.
24.) Save all the roi. Select algorithm for classification.
25.) Before going for classification you can see a preview with the option provided as classification preview. Now Click on the plus sign and click on the area where you want to see the preview.
Image classification in QGIS
26.) Take a look at the preview. If this is the output you want you can go for final classification or you can make other ROI. Click on perform classification for final classification. This process will take time for classification. After the classification is done. Click on post processing tool icon and generate classification report.
Explore this plugin for more option. You will have a good classified image after practicing. Hope this tutorial helps you to explore the tool for classification with the help of QGIS software. If you want to share or have doubts or facing difficulty in implementing the steps, do comment below in the space provided below.
Here we will see how to georeference a map with the help of another georeferenced map in QGIS (Quantum GIS). Georeference is a process to associate geographic location coordinates to any kind of physical object which is physically present over a Raster image map or to a physical map, with help of other georeferenced data or with know location coordinates of some points of image which is effectively called as control points. It is one of the important concept of GIS (Geographical Information System). We have already discussed about how to Georeference Map with the help of know control points.
Georeference a map with the help of another georeferenced map:
1.) Open QGIS and Load the georeferenced map, by selecting Layer -> Add Layer -> Add Raster Layer or by directly selecting Add Raster Layer from Layer panel as shown below.
2.) After loading the file, from the menu select Raster and click on Georeferencer to select Georeferencer.
3.) In the Georeferencer window which is open up by above step, select Add Raster Layer icon to load non georeference map.
4.) Click add point and select a point on your map. In the pop up window click from map canvas.
Georeference a map with the help of another georeferenced map
5.) Select location in the georeferenced map same as the location you selected in non-georeferenced map. You will see it will load the coordinates.
6.) Click ok.
7.) Likewise select at least four points in different direction. Click transformation setting icon button as shown below in image.
8.) Select any one Transformation Type and provide your output raster name.
Georeference a map with the help of another georeferenced map
9.) Click start Georeferencing button from the Georeferencer window.
10.) Select CRS same as the georeferenced map. In our case it is WGS 84. Close georeferencer. You will see georeferenced image in canvas. Note the coordinates.
Georeference a map with the help of another georeferenced map
I hope this article would be helpful for you to know the basics of how to georeference raster image with the help of another georeferenced map. If you are facing problem in implementing the process do comment below, so that we can discuss over it.
Geographic Information System is a system intends to capture, Store, manage, manipulate, analyze the data. 
2.) Click on select tool from toolbar as indicated in the image.
3.) Your Desktop QGIS screen will look like this below image.
