Using Symbology in ArcMap 10.2

Using Symbology feature in ArcMap 10.2 helps the User to better convey the map information to the audience. Symbols define the way points, polygons and polylines are displayed on the map to express information in qualitative or quantitative form .

In this presentation, we will be showing how the Symbology feature in ArcMap 10.2 used to express information about the theme- Population.

We will use a shapefile of Nigeria with attribute table containing data on the 2006 Census data such as the Total population per State, Male and Female population per State to carry out the demonstration. We will look at three ways of symbolizing the data.

- Qualitative- deals with non-quantitative criteria like the regional divisions of the country.For this, we will use the values in the Region Field to group the states into different regions.
- Quantitative- deals with actual quantities estimated in figures. For this, we will be using census_Tot field .
-Qualitative and Quantitative- here the two parameters can be combined to symbolize information on a map.

Shapefile Nigeria


Attribute Table of the Shapefile Population Data. We will working with Fields= Census>Tot (Total Human population in the State), census_Mal (Population of Males in the State) and census_Fem.(Population of females in the State)


Right Click on Layer> Properties. A Layer Properties dialog box will open.


Click on the Symbology Tab and the default shown on the Left hand panel is Single Symbol.


Qualitative display
We want to display the map showing different regions in the Country. Remember on the Attribute table each State is under a region with a regionId
We change the Single Symbol to Categories (red box), Our Value Field is Region (brown box). Then simply click Add All Values and the different regions are loaded in from the Value field (green boxes). Click Apply to view the result.


The map display has divided the country into different regions by grouping the states. In the red boxes, the values in the Field-Region are displayed on the Table of Contents under the layer. Symbology is based on categories with unique values.


Quantitative Display
Next, we want to work with the census_Tot field which is numerical or quantitative. We want to use the symbol feature to group states by population size.
Click on Quantities> Graduated colors(red box), Fill in value field as census_Tot and the figures will appear depending on the Classification into Classes (red box to the right). Once Classes are selected, the census_Tot data will be classified along a quantile color ramp.


The population data is now classified according to the census_Tot field (red boxes) showing the population sizes of the States from Low-medium-High using graduated colors.


In this illustration, we switch to using Graduated Symbols to visualize the population sizes of the States.(see red boxes)


Under the Quantities, the User can visualize the data as Charts. The Chart below represents the ratio of male to female in each state.


Combination of Qualitative and Quantitative – Multiple Attributes
Symbology features allows the User to combine qualitative symbols with quantitative symbols using the Multiple attributes option. In the demonstration below, there is a combination of attributes from the regions field (States according to regional division) and the census_Mal (Population of males per State) . Polygons grouping the States into their respective regions and the point symbol represent the relative sizes of the male population in the States. The red boxes indicate the important classification and Symbology system applied.


Start practicing folks and let us have your feedback and comments.

Converting KML layers created in google earth images to feature layers in ArcMap using ArcToolBox

CLICK ON THE LINK TO VIEW AND DOWNLOAD PROCEDURE

We saw two advantages from this process and we are still working on other inconsistencies.

1. The slight shift and inconsistencies generated when having to georeference images will be reduced if not totally eliminated.
2. Google satellite imagery can now serve as a ground control for the GPS when ground truthing exercises are carried out.


Task
We will demonstrate how to import vector layers created from google earth in ArcMap using ArcToolBox.

CLICK ON THE LINK TO VIEW AND DOWNLOAD PROCEDURE

Uploading Feature layers from ArcMap 10.2 to store as waypoints, routes and tracks in a GPS receiver

Task
To upload feature layers in Arcmap 10.2 and store them as waypoints, routes and tracks in a GPS receiver.

Things to note

- Arcmap 10.2 just like google earth, only recognizes two types of GPX files- Waypoint and Tracks.
- ArcMap 10.2 has a GPS extension but this comes with a serial com port connection.
-DNR GPS plugin seems to have some technical issues in ArcMap 10.2 but works great with Arcmap 9.

Thanks for viewing, head for the comments sections or feedback page and share your thoughts.

Tracing polygon features from a google satellite image and uploading them to GPS receiver using DNRGPS

Overview
Our previous post dealt with a similar process but instead of polygons we were uploading routes. This post will demonstrate how polygon or area features can be digitally traced out on a google satellite image in google earth, saved as KML and then uploaded and stored as tracks in a GPS receiver.

Task
- Digitally trace out a polygon feature from a google satellite image in google earth and
Save the place as a Kml file format.
- Load it into DNR GPS and convert it to GPS Xchange file format(*gpx)
- Upload it as Tracks to the GPS receiver.

Procedure

1. Launch google earth and locate your polygon of interest. Pick the ADD POLYGON tool and digitally trace out the area. Give it a name in the dialog box and check that it is in the Places window (red boxed). Right Click on the polygon (area feature) >Save place as. The Save as dialog box will open; make sure it is save type as KML.


2. Launch DNR GPS and Go to File>Load From> Google Earth> My Places


3. An Open database dialog box will come up. Go down to Google Earth My places, click on it and click ADD (red boxed)


4. Fill the dialog box and OK to access the data in google earth my places and Press OK. A loaded data complete message will appear and the data will be loaded into DNR GPS.


5. Select name as the TRIDENT which simply means Type identify. Our Type identity is area feature


6. The kml file area feature will be loaded into DNR GPS


7. Go to File>Save to> File. In the Save as dialog box, save type as GPS Xchange Format



8. In this dialog window, Check Tracks as polygons are stored as Tracks in a GPS receiver. A message box will notify that the file has been successfully saved.


9. Connect the GPS receiver, Go to Tracks>Upload


10. Window will open to prompt you to name the uploaded data, click OK. A message box confirming Upload complete will pop up.


Check the GPX folder of the GPS receiver Drive in C. for the uploaded track.

A week break for the field

We, the folks at mapsnigeriainitiative, would like to thank all our viewers for their patronage in the last few weeks. We hope you are enjoying our content and  remain  grateful for all the views, comments and feedback we have received thus far.

We are taking a week off serious blogging as we head out field mapping later this morning. We promise to be back on Sunday with fresh content, newer techniques and great posts for you all. For the mean time, we will still be available online posting replies to comments and feedback.

Keep practicing and let the comments and feedback flowing in .

Watch out for our new page – announcements and offers. We are working towards posting it up soon.

Happy blogging

Digitizing polygon or area features on a raster image using Arcmap 10.2

Polygon or Area features are those that have the same starting and end point.

In this post, we will show the following-

- digitize area features on a raster image

- create polygon shape files in arcmap 10.2

Click on link - digitize polygon features using arcmap 10.2 and watch the video presentation.


Start digitizing folks, send your feedback and comments

Georeferencing a raster image using ArcMap 10.2

We have in an earlier post dealt with doing some georeferencing in QGIS. This time around, using Esri ArcMap, we will georeference a scanned or rasterized jpeg image of a quarter degree sheet 1:50,000 SHEET 261 (Ibadan NE) using the WGS84 geographic coordinate system.


Tips

• Make sure the scanned or raster image is in your working folder in the C: drive.
• Assign a geographical coordinate system to the layer in the Table of Contents before bringing in the image for georeferencing.
• Its better to allow the system build pyramids when adding the image, so click yes when prompted.

As earlier noted, there are other things which may only be learnt when the process is practically carried out by the viewer. That's why we like to hear from you and shine light on those grey areas.
Watch the tutorial video carefully as it tries to make the process as simple as possible. Click this link for the video- https://drive.google.com/file/d/0B8z8JZ83pZMaaUc4RGY2empmaXc/view?usp=sharing


Note that a left mouse click is indicated by the red burst of light at the tip of the mouse pointer, while a yellow burst indicates a right mouse click.

Esri 60 day trial for ArcMap and ArcGIS Pro- A window of GIS opportunity

After our post on Georeferencing in QGIS, we received a couple of feedbacks by core Esri fans. In their feedbacks, they brought up the fact that since for the mean time the popular applications of ArcGIS and MapInfo still held sway in Nigeria, I should also put up demos on ArcGIS as this would enable a level playing ground for readers to examine both applications.


So the more pertinent question? How can I lay my hands on ArcGIS software to practice the lessons without having to purchase a pirated copy? I get that question from a lot of students and graduates. Well it is simple but it comes with a price tag, yes.


Esri has made available free download of a single license edition of ArcInfo and ArcMap or now called Arcmap and ArcGIS Pro- on its international website but before you shout hurray, here comes the price tag. It is only a 60 day free trial version!! Don’t despair because for any serious minded person, believe me, two months and a dedicated use of online resources can make a big difference in your proficiency in the use of ArcGIS software. You can always proceed in the bliss of QGIS when the trial is over but with the confidence that if challenged with ArcGIS, you won’t wither.

let us remember that the problem with most of us is that we do not adhere to a dedicated software study plan. Instead we leave it to the vagaries of time. Working with a trial software demands that one should make the best possible use of it in the trial period. I have watched with sadness as students use free school wifi to download gigabytes of films and TV series instead of enriching their knowledge of IT, especially professional softwares that will enhance their skill base. So will you blame the school when computer graduates cannot write ordinary html. Javascript etc?

Back to the topic at hand. For the serious minded ones, please follow the steps to download Esri ArcGIS to your laptop or desktop. This are outlined in the link below
https://www.dropbox.com/s/rm6phhhw1cbj0c6/Downloading%2060day%20Free%20trial%20of%20ArcMap%20and%20ArcGIS%20Pro.docx?dl=0
Note the following hardware and software requirements-

• Be sure your laptop has at least 2G of RAM. ArcGIS allocates almost 1gig of RAM for processing. Check your PC configuration.
• ArcMap requires Microsoft .NET Framework 3.5 SP1 and Microsoft Internet Explorer version 7 or newer.

Hope you are already downloading as the next few posts will deal on working with ArcGIS.
Am expecting your feedbacks folks. Just go to the feedback page and roll them in.

Digitizing point, line and polygon features into shape files QGIS

This is a continuation of our QGIS series. We started with Georeferencing (See previous post ‘Georeferencing a raster image using QGIS’) and today we will demonstrate how to digitize a raster image to create point, line and polygon shape files.


Watch and follow the video lessons carefully and send any questions, comments or observations through our feedback page. I must chip in that it is quite tasking to show the process of digitizing offsite, but we hope it is made as simple as possible. Sorry, we couldn’t add sound as this would make the video too heavy to embed, we are working on that technicality.


Tips

• Mouse Right Click on the Layer when you want to Open the attribute table
• Make sure the layer you are creating and the raster image have the same spatial reference. Note how the spatial reference was changed in the video – ‘Digitizing polygon features’.
• The ID field on the attribute table serves as index key to join database or tables.
• Right click when u finish tracing a feature so the table to fill will pop up.
• To delete the trace, open the attribute table, select it and use the trash bin icon to delete it.

Point features -https://drive.google.com/file/d/0B8z8JZ83pZMaTnlyT0kzTUtSOVE/view?usp=sharing
Line features https://drive.google.com/file/d/0B8z8JZ83pZMabVJLekEwQTRfR1E/view?usp=sharing
Polygon features https://drive.google.com/file/d/0B8z8JZ83pZMaT2p2OW9fQ0RBZ1U/view?usp=sharing


Hope you have started practicing yourself. remember to feel  free to comment.