Thursday, August 23, 2018

Cartographic Map Layout Designs


An important characteristic of maps is that they need to be both functional and aesthetically pleasing. Therefore, designing a quality map is more than just a scientific process, it takes your creativity, artistic and design skills to get the job done.

The craft of map making is called cartography, which is both the art and science of map making.

Well prepared map should contain the following elements on its map layout design:- map body, legend, title, north arrow (directional indicator), labels, scale, grid/graticule lines, citation, border and inset map.

Map Elements

1~ Map body: This is usually the largest element on a map layout. It is the primary focus on a map layout as it shows/display the geographical message and purpose of the map.

2~ Legend: This is the map element that lets the map reader know what each symbol on the map stands for. It help in understanding what information is been communicated on the map.

3~ Title: This is usually the largest text of the map and provides a short, descriptive, statement about the purpose of the map, and may include  other pertinent information, such as the timeframe for which the map applies.

4~ North arrow (directional indicator): This is the map element that tells the map reader the North, South, East and West directions on the map.

5~ Labels: These are textual elements written to further explain what an object is on the map. Most at time, map user will need explicit information apart from the on on the legend, so the "Labels" are there to help out. Often, it is in the attribute table of the features.

6~ Scale: This is the ratio of measurements on the map to that on the true ground. It is usually displayed in linear graphic or written text.

7~ Grid/Graticule lines: There are references a coordinate, or measurement system, that the map user can use to derive the location, coordinates.

8~ Citation: This is also know as "Metadata". It is the documentation for the map and the data displayed on the map. Metadata should include items such as the date the map was created, the author of the map, and data sources for the data shown on the map body.

9~ Border/Neat line: This is a frame for the map which typically surrounds the entire map. It separate the map from the surrounding page or elements.

10~ Inset map: This is a smaller map body that shows from which the main map body was extracted from. It help in making sense of where the main map is located especially for unfamiliar maps.

Sunday, August 19, 2018

Transforming Nigeria Minna Coordinates (epsg: 4263) to WGS 84 (epsg: 4326) using QGIS


Different countries have different local coordinate geographic reference systems (CRS), Nigeria is not an exception. One of the most developed and used local geographic CRS in Nigeria for general mapping is the "Minna  (epsg: 4263)".

EPSG - "European Petroleum Survey Group" is the organization in charge of maintaining different datum, coordinate reference systems and coordinate transformations around the world which may be global, regional, national or local in application. It is also worthy to know that the organization is also called: "International Association of Oil and Gas Producers" (IOGP).

A search on for "Minna" reveals both geodetic and projected CRS. Our focus in this article is on the newest Minna geodetic (geographic) datum with EPSG code 4263, that has it measuring units in degrees as seen below.

Note that there is a deprecated version of the Minna datum with EPSG code as: 62636405

"Minna" geodetic datum was first derived from the "Nigerian National Coordinates System" which is no longer in use. "Minna" geodetic datum is suitable for use in Nigeria - onshore and offshore. "Minna" references the Clarke 1880 (RGS) ellipsoid and the Greenwich prime meridian. Minna origin is Fundamental point: Minna base station L40. Latitude: 9°38'08.87"N, longitude: 6°30'58.76"E (of Greenwich). Minna is a geodetic datum for Topographic mapping.

It has the following Extent: 2.66°E, 1.92°E, 14.65°N, 13.90°N (upper long., lower long., upper lat., lower lat.).

Friday, August 10, 2018

Getting Google Maps API key in 2018

If you are an old developer who uses the Google Cloud Platform Console developer's tools such Google Maps API key to power application, you will notice that getting a copy of the maps API key has slightly changed in the month of July, year 2018.

Unlike in previous years, when signing up for a copy of the key is just a matter of having a Google account and then putting up a simple request. Today, Google do request for credit card information before the sign-up process is completed. So, the big question now is: Is there no more FREE quota for the Google Maps API key anymore?

Creating a Google Maps API Key
Even though, Google now requests for your credit card information before the sign-up for a key there is still the free quota usage on the API key as usual. Google says: the reason why it request for the credit card information before the sign-up, is to make sure bots/robots don't sign-up for the keys. Also, there is no auto charge on your card when you use up the free trial/quota on your key.

Before you are charged, you will have to manually upgrade your key to a paid plan.