Tuesday, December 11, 2018

How to save High Resolution Image from Google Earth Pro

I have seen many "Google Earth Pro" users taking screenshots of the images instead of saving it directly in high resolution, probably because the "Save Image" function is a little bit obscured. This post will guide you through saving a high resolution image from "Google Earth Pro" released in the year 2018.


At first when you click on the save button, nothing seems to happen aside the "Untitled Map", "Compass", "Scale" and empty "Legend" boxes that pop-up on the screen.



If you look closely, just under the "Untitled Map" box, there appear the "Save Image" tool bar. On that very tool bar, you will see the "Save Image" button. That is the button you actually needed to save the image.



But before you save your image, you will definitely like to update the map title and do other settings. This can be done from the "Map Options" button on the "Save Image" tool bar.



You could also select your preferred image resolution from the tool bar.

Thank you for reading.

Tuesday, December 4, 2018

An Atlas Map of Nigerian States - QGIS Map Report Tutorial

QGIS 3 comes with a nice feature for creating collection of maps (aka Atlas). This feature is called "Report" in QGIS 3, it works closely like the "Print Layout" (formerly know as "Print Composer" in QGIS 2).

You can access the "Report" window from the project menu as seen below...



In the next few lines, I will demonstrate how to generate a map report in QGIS using the Map of Nigerian States. See the document we want to produce at the end of this tutorial here...



Saturday, December 1, 2018

The Difference between the United Kingdom, Great Britain and England

Often people confuse these three: United Kingdom, Great Britain and England. As an example, in sports different names are used for Olympic games different from football World Cup game and many others.

Below is the map of the world and the area in question is this tiny mass of land within the red mark.


Lets zoom in and look at the map closer, the whole of that area is the "British Isles" consisting of five countries which is categorized into to named: Ireland and Great Britain.

Ireland consist of two countries "Republic of Ireland and Northern Ireland", while Great Britain consist of three countries "England, Scotland and Wales".

United Kingdom is made up off the whole of Great Britain and part of Ireland. That is all the countries in Great Britain ("England, Scotland and Wales") are in United Kingdom and in Ireland only Northern Ireland is part, Republic of Ireland isn't part of United Kingdom.

Hmm! This sounds complicated, right? Let clarify this by visualizing it on a map.


British Isles = Ireland + Great Britain

Here purple color for Ireland and blue color for Great Britain to clearly see to two different regions.



Ireland = "Republic of Ireland + Northern Ireland"
Great Britain = "England + Scotland + Wales"


United Kingdom =  "England + Scotland + Wales + Northern Ireland"


I hope that was clear and succinct.
Thank you for reading

Wednesday, November 14, 2018

Drawing Site Plan with DraftSight a FREE Alternative to AutoCAD

There are many low budget or free Computer-Aided Design (CAD) software alternatives to Autodesk's AutoCAD out there and DraftSight is one of the best alternatives I have used.


Using the free version, you could plot or draw a professional survey plan just as you would do in AutoCAD. In this blog post, I will demonstrate how you will do just that using the free DraftSight CAD software. So, download the DraftSight here and follow the instructions below to activate it.

Instruction 1: Download the software from the link above and launch it to install



Instruction 2: Select Free option and click the next button as seen above.

Instruction 3: Accept the terms in the license agreement and install



Tuesday, November 13, 2018

The difference between "Geocoding" and "Geolocation"

These two terms are often confused by users in of spatial data. Here is a quick explanation to help clarify the difference between the two. Both of these terms are consistently been misuse by people within the geospatial community.

Address: "Abuja International Conference Centre, Herbert Macaulay Way, Abuja, Nigeria"
Coordinates (in 3D): "Latitude: 9.0438014, Longitude: 7.4919024, Sea level: 503m"



Looking at the landmark address above and its corresponding coordinates in three-dimension (3D), we could say:-

Geocoding - means to 'Convert addresses to geographic coordinates, or the reverse'. While  Geolocation - means to 'Return the precise location of a device based on Wi-Fi or cell towers'.

More elaburate explanation from Wikipedia, the free encyclopedia:-

Geocoding is the computational process of transforming a physical address description to a location on the Earth's surface (spatial representation in numerical coordinates). Reverse geocoding, on the other hand, converts geographic coordinates to a description of a location, usually the name of a place or an addressable location. Geocoding relies on a computer representation of address points, the street / road network, together with postal and administrative boundaries.

Geolocation is the identification or estimation of the real-world geographic location of an object, such as a radar source, mobile phone, or Internet-connected computer terminal. In its simplest form geolocation involves the generation of a set of geographic coordinates and is closely related to the use of positioning systems, but its usefulness is enhanced by the use of these coordinates to determine a meaningful location, such as a street address.

Sunday, November 4, 2018

Installed Python Libraries on QGIS Vs Anaconda


As some one who uses Python for Geospatial development, I was tempted to know what modules are installed on QGIS python environment compared to that of Anaconda python.

On the console of the two platforms, I executed this: help('modules') and I got the following out puts.


QGIS:


MetaSearch console mkgraticule sre_parse
PyQt5 contextlib mmap ssl
__future__ copy mmapfile sspi
_ast copyreg mmsystem sspicon
_asyncio crypt mock stat
_bisect csv modulefinder statistics
_blake2 ctypes msilib string
_bootlocale curses msvcrt stringprep
_bz2 cycler multiprocessing struct
_codecs datetime nbformat subprocess
_codecs_cn dateutil netbios sunau
_codecs_hk db_manager netrc symbol
_codecs_iso2022 dbi networkx symtable
_codecs_jp dbm nntplib sys
_codecs_kr dde nose2 sysconfig
_codecs_tw decimal nt tabnanny
_collections decorator ntpath tarfile
_collections_abc difflib ntsecuritycon telnetlib
_compat_pickle dis nturl2path tempfile
_compression distutils numbers textwrap
_csv doctest numpy this
_ctypes dummy_threading odbc threading
_datetime easy_install ogr time
_decimal email ogrmerge timeit
_dummy_thread encodings opcode timer
_elementtree ensurepip operator token
_functools enum optparse tokenize
_hashlib epsg_tr os trace
_heapq errno osgeo traceback
_imp esri2wkt osr tracemalloc
_io exifread owslib traitlets
_json expressions parser tty
_locale faulthandler past turtle
_lsprof filecmp pathlib types
_lzma fileinput pbr typing
_markupbase fnmatch pct2rgb unicodedata
_md5 formatter pdb unittest
_msi fractions perfmon urllib
_multibytecodec ftplib pickle urllib3
_multiprocessing functools pickletools uu
_opcode future pip uuid
_operator gc pipes venv
_osx_support gcps2vec pkg_resources warnings
_overlapped gcps2wld pkgutil wave
_pickle gdal platform weakref
_pydecimal gdal2tiles plistlib webbrowser
_pyio gdal2xyz plotly win2kras
_random gdal_auth poplib win32api
_sha1 gdal_calc posixpath win32clipboard
_sha256 gdal_edit pprint win32com
_sha3 gdal_fillnodata processing win32con
_sha512 gdal_merge profile win32console
_signal gdal_pansharpen pstats win32cred
_sitebuiltins gdal_polygonize psycopg2 win32crypt
_socket gdal_proximity pty win32cryptcon
_sqlite3 gdal_retile py_compile win32event
_sre gdal_sieve pyclbr win32evtlog
_ssl gdalchksum pydoc win32evtlogutil
_stat gdalcompare pydoc_data win32file
_string gdalconst pyexpat win32gui
_strptime gdalident pygments win32gui_struct
_struct gdalimport pylab win32help
_symtable gdalmove pyodbc win32inet
_thread gdalnumeric pyparsing win32inetcon
_threading_local genericpath pyplugin_installer win32job
_tracemalloc getopt pyproj win32lz
_warnings getpass pythoncom win32net
_weakref gettext pytz win32netcon
_weakrefset glob pywin win32pdh
_win32sysloader gnm pywin32_testutil win32pdhquery
_winapi gzip pywintypes win32pdhutil
_winxptheme hashlib qgis win32pipe
abc heapq queue win32print
adodbapi hmac quopri win32process
afxres html random win32profile
aifc http rasutil win32ras
antigravity httplib2 re win32rcparser
argparse idna regcheck win32security
array imaplib regutil win32service
ast imghdr reprlib win32serviceutil
asynchat imp requests win32timezone
asyncio importlib rgb2pct win32trace
asyncore inspect rlcompleter win32traceutil
atexit io runpy win32transaction
audioop ipaddress sched win32ts
base64 ipython_genutils scipy win32ui
bdb isapi secrets win32uiole
binascii itertools select win32verstamp
binhex jinja2 selectors win32wnet
bisect json servicemanager winerror
builtins jsonschema setuptools winioctlcon
bz2 jupyter shapely winnt
cProfile jupyter_core shelve winperf
calendar keyword shlex winreg
certifi lib2to3 shutil winsound
cgi libfuturize signal winxpgui
cgitb libpasteurize simplejson winxptheme
chardet linecache sip wsgiref
chunk locale sipconfig xdrlib
cmath logging sipdistutils xlrd
cmd lzma site xlwt
code macpath six xml
codecs macurl2path smtpd xmlrpc
codeop mailbox smtplib xxsubtype
collections mailcap sndhdr yaml
colorsys markupsafe socket zipapp
commctrl marshal socketserver zipfile
compileall math sqlite3 zipimport
concurrent matplotlib sre_compile zlib
configparser mimetypes sre_constants


Sunday, October 21, 2018

Accessing JSON nested object with python

This blog post highlights the key components to look at when parsing a JSON file with deep level of nested objects and variables.

First thing first, is to load in the file using: with statement...

The nested/child objects can then be accessed like this...
obj1['obj1a']['obj1a_1']['obj1a_2']['obj1a_3']...,
obj2['obj2a']['obj2a_1']['obj2a_2']['obj2a_3']...,
obj3['obj3a']['obj3a_1']['obj3a_2']['obj3a_3']... etc


Take this example, where we have a JSON object with parent object "requests" which contains "0" which also contains "responseCode" which also contains more children (in this case 3 children as seen above). Another child object at the same level with "responseCode" is "testPassFailCounts" which contains 217 more children.

That JSON structure is nested as follow:- requests >> 0 >> responseCode >> ... >> ... >> ... etc. Use a JSON viewer or reader such as JSON Editor Online to visualize the structural arrangement of your specific JSON file.

Now, to access any level of nested child in python follow this code snippet:-

import json

with open('name_of_file.json', encoding='utf-8') as f:
    data = json.load(f)
    
responseCode = data['requests'][0]['responseCode']
testPassFailCounts = data['requests'][0]['testPassFailCounts']

len(responseCode) # will return 3
len(testPassFailCounts) # will return 217


That is it!
Happy coding.

Tuesday, October 16, 2018

TkInter Open select file dialog windows from CMD

Are you writting a script for non tech savvy people that will require them to supply some file path like this: C:\Users\PC Name\Desktop\folder1\folder2\folder3\file-name.csv

As you already guess, many non-tech savvy individuals wont be able to type in such kind of file path to use you script. A work around this is to provide a Graphical User Interface (GUI) to the script, where is easier and user friendly to work with.

Here below is a simple solution using default GUI library that comes with python. This script gets an input file from user interactively via GUI, instead of using the CMD. It is written for both python 2 and 3:-

try:
    # for Python2
    from Tkinter import *   ## notice capitalized T in Tkinter
    from tkFileDialog import askopenfilename

    Tk().withdraw()
    polyfile1 = askopenfilename(title="Select original line file:", filetypes = (("comma-separated value (CSV) files","*.csv"),("all files","*.*"))) # show an "Open" dialog box and return the path to the selected file

    # Using the file...
    print ('Do something with the file in Py2', polyfile1)


except ImportError:
    # for Python3
    from tkinter import *   ## notice lowercase 't' in tkinter here
    from tkinter import filedialog

    Tk().withdraw()
    polyfile1 = filedialog.askopenfilename(title="Select original line file:", filetypes = (("CSV files","*.csv"),("all files","*.*"))) # show an "Open" dialog box and return the path to the selected file

    # Using the file...
    print ('Do something with the file in Py3', polyfile1)




Running the script above should open the select file window as seen below.

That is enjoy the script.

Wednesday, October 10, 2018

How to Upload CSV file of Projected Local Coordinates onto ArcGIS Online

The cloud/web based version of ESRI ArcMap (ArcGIS Online) has come to stay. However, unlike the desktop version (ArcMap) that support many local coordinates systems, ArcGIS Online currently supports geographic coordinates in WGS84 but hardly reads local projected coordinates such as Nigeria Minna Datum UTM Zone 32N, StatePlane coordinates NAD 1983 (e.g StatePlane_Illinois_East epsg: 102671), Hong Kon 1980 Grid System, etc

If you try to upload such CSV file that have projected coordinates on "ArcGIS Online", you will encounter this error that says: "The layer was not created because no locations could be found. Make sure your data has valid location information".


The is because the coordinates in the CSV file are projected in UTM Zone 32 - Minna Datum (used in Nigeria region - EPSG: 26332).

Note: If you getting this required screen error: Location fields not fully specified. Then it means you did not select the correct location fields from the CSV file.


So, be sure to select the correct fields, that is Eastings for Longitude and Northings for Latitude.



If you are getting this error that says: "The layer was not created because no locations could be found. Make sure your data has valid location information", then you have to do one of the following to successfully upload you CSV data file.

Solution 1: Convert the projected coordinates to Geographical coordinates (that is convert from easting & northing to longitude & latitude).

Solution 2: Convert the CSV file itself to GeoJSON. The reason why this GeoJSON work even though the coordinates are still in projected form is because of the attribute or object in the GeoJSON file that defines the correct coordinates system that the coordinates represented.

Wednesday, October 3, 2018

The Basics of Map making With QGIS, GIMP and Inkscape

Making a modern print ready map will require one or both of the following, namely:
1) Scientific analysis
2) Art and design

In other words, the maps you see are both products of scientific charts as well as works of art and design.

GIS software such as QGIS does the science part better, illustration software such as GIMP and Inkscape handles the art part better.

If you are making a map to accurately/precisely visualize some variables based on scale, then you probably need a scientific map done with the QGIS/ArcGIS. If on the other hand, your map is simply to illustrate some variables not accurately/precisely to scale, then an illustration software like GIMP/Adobe Photoshop for raster editing or Inkscape/Adobe Illustrator for vector editing should be enough to get the job done.

With that said, it is a common practice these days to combine both the scientific and art & design software to finish a map layout. That is you will accurately prepare your map to scale in a scientific software and then complete the aesthetic layout using illustration software. Let's take a look at how this can be done below.

QGIS can handle the majority of vector and raster operations and most of the cartographic work. However, from a cartographic perspective, Inkscape and GIMP are primarily used to finish maps created within a GIS. Inkscape handles vector maps, while GIMP is best suited for raster maps. People often use GIMP to fine-tune coloration of a map. Inkscape is often used to add, for example, custom arrows to maps or add shadows to lines and polygons.

Basic Steps for making maps with QGIS, GIMP and Inkscape:-
1) Get the data
2) Load the data into QGIS
3) Symbolise and style the map according to the information the map wants to communicate
4) Prepare and compose it for printing
5) Export it as image for further fine-tuning in GIMP or export is as SVG file for fine-tuning in Inkscape

Note: If you need to have the map in print-ready magazines, brochures, posters, newsletters or other forms of page layouts and typographic quality text and images, then you will need use a desktop publishing application such as Scribus/Microsoft Publisher/Adobe Indesign or Pagemaker.



Conclusion
You should always bear in mind that QGIS understand all the science of map making which includes various GIS, Geodesic and Cartographic processes. GIMP, Inkscape and Scribus are there to support you in archiving a quality print/publish ready info-graphic maps.

Sunday, September 30, 2018

3 sure ways to Land your first GIS and Mapping Job - as a freelancer, contractor, or small business owner

Dear reader,

To effectively Build your career in this industry, you need a solid educational background by taking classes in geography, surveying, geodesy, cartography, GIS, spatial analysis, database management, web technologies, and programming. A common problem with GIS/digital map learning and related institutions is that they never guide you on how/where to find good paying jobs after they have impacted the necessary skills on you.

"It is one thing to acquire the skills and it is a different ball game to make money from your mapping skills".

Many classes in the formal education tend to focus more on the theoretical concepts, so I strongly encourage you to look on to acquiring production skills afterward. Learning platforms such Udemy, Lynda, Udacity, PluralSight, Boundless etc tend to have more practical and real-world production oriented courses. Take your time master those once that suit your career before jumping in the labor market.

In this post, I will open up your eyes to three ways to get your first GIS and Mapping Job. I assured you of your first GIS and Mapping Job or some passive income in three months time before settling on a permanent job, if you follow the advice below diligently... Let's do it.

Here are the three ways to land your first GIS and Mapping Job:-

1- Search and apply for opening in Government and Private sectors:
Note here, you should be able to accept or tolerate delay, problems, or suffering without becoming annoyed or anxious (it requires your maximum level patience).

There are many GIS entry-level jobs and internships often targeted at recent graduates. Many Government sectors at local, state or federal level have GIS/Mapping needs and this varies from one country to another. You will have to refer to your specific country to see what government organizations fits into your skills.

To give you some ideas, there are many different government industries that have GIS and mapping departments some of them include: health, agriculture, transportation, construction, real estate, mining, communication, disaster management, research institutes etc. Watch out for opening in some of these areas and push in when you find one.

On the other hand, there are privately run startups or companies you can work with. If you take away the big names, it is sometimes difficult to know what other options exist that you can apply to. Here I will show you how the search for them.
  • Conferences, meet-ups and workshops
  • Geospatial Magazines and other publications
  • GIS Forums
  • Subscribe to newsletters
As an example, below is newsletter from Geomares Publishing. Just that one newsletter alone, you already have access to so many potential employers of your GIS and mapping skills. There are all sort of information including job postings there to keep your eyes on for possible job openings.


The newsletter ofter covers the areas which include "Marine Product Updates, Geomatics Product Updates, GIM International Newsletter, Hydro International Newsletter, Offers and Promotions, Geomatics World Newsletter and GIS Professional Newsletter".

This is just one, there are many more magazine out there to subscribe to and get tones of current and relevant information in the GIS and Geospatial domain. Here is a list below, remember to search within your locality for local alternatives.


Most of these magazines are published few a times annually, but when they do get published be rest assure of finding ample of information including job listings and potential companies in the industry that could hire you.

I strongly encourage you subscribe at least to the soft copies if you can't afford the hard/printed copies and watch out for job openings.

Tuesday, September 25, 2018

QGIS 'Add Delimited Text Layer' with Special (Chinese Language) characters

Add Delimited Text Layer in QGIS isn't new. In fact it is the easiest way to import a list of coordinate points in .CSV file into QGIS as a map layer.

What is new here is that the CSV file has some columns with Chinese characters. And such characters are not well read in CSV file formats. For example here below is how the original data looks in excel .xlsx format.



After saving it as .csv for import into QGIS via "Add Delimited Text Layer" menu, it looks this below. Obviously this is not what is expected in the CSV file.



Excel (.xlsx) is not recognized in QGIS "Add Delimited Text Layer", so we can't use the excel file directly. We have to find a way for the CSV file to read the characters correctly or we look into using another file format such as the text file.

Sunday, September 16, 2018

Map of the Six Geopolitical Zone in Nigeria showing total number of registered voters

There are Six Geopolitical Zone in Nigeria as listed below. The six geopolitical zones of Nigeria is a major division in modern Nigeria, created during the regime of president General Sani Abacha. Nigerian economic, political and educational resources are often shared across the zones (source wikipedia).



North Central (loosely known as Middle Belt):

  • Benue
  • Kogi
  • Kwara
  • Nasarawa
  • Niger
  • Plateau
  • Federal Capital Territory


North East:

  • Adamawa
  • Bauchi
  • Borno
  • Gombe
  • Taraba
  • Yobe


North West:

  • Jigawa
  • Kaduna
  • Kano
  • Katsina
  • Kebbi
  • Sokoto
  • Zamfara


South East:

  • Abia
  • Anambra
  • Ebonyi
  • Enugu
  • Imo


South South:

  • Akwa Ibom
  • Cross River
  • Bayelsa
  • Rivers
  • Delta
  • Edo


South West:

  • Ekiti
  • Lagos
  • Ogun
  • Ondo
  • Osun
  • Oyo

Friday, September 14, 2018

Quick Python Guide to Extracting Data from MyFantasyLeague.com API

Introduction to API
Many organizations uses the Application Program Interface (API) to allow developer access some of their data. Access to data set via API is usually controlled by using the "API Key or client ID" which can be obtain by registering for free or at some cost.

A data set that changes quickly is better served through an API instead of a static database. To access the API data you have to send request to the remote server where the data lives. In most cases, an API data lives on the remote server in XML or JSON format.

To learn more about specific API structure make sure you take a look at it's documentation which is usually made available by the provider.


MyFantasyLeague.com API
In this post, we will take a look at the open data on MyFantasyLeague.com API. Specifically, we will send request to get the "players" data. The process discussed here will work for any request type with little or no modification.

First, before you continue I recommend you read the developer API page.

Step 1: Identify where the data lives and get its request url
From the request test page, you will that the players' data lives on this url below:-
XML = http://www03.myfantasyleague.com/2018/export?TYPE=players&DETAILS=&SINCE=&PLAYERS=&JSON=0


JSON = http://www03.myfantasyleague.com/2018/export?TYPE=players&DETAILS=&SINCE=&PLAYERS=&JSON=1


Step 2: Get the url and parse it into python
Now that we know where the data we needed is located, we parse it into python. I prefer using JSON, so I will use the JSON url to collect the data into pandas data frame for further processing.


Note that you will need to identify the JSON element root and child to get hold of the data in pandas. To easily identify the element roots, use an online JSON reader such as this...



If everything was successful, the above script should produce the dataframe table below:-





Step 3: Do something useful with the dataframe data. You can save it to a database or CSV file.


That is it!

Sunday, September 2, 2018

Simple Map Animations using QGIS and GIMP

Hello there,
It is no longer new that most aesthetically pleasing maps out there have some of it elements accomplished with photo or graphics editing software.

In this post, you will see the important of having a graphics editing tool in your GIS tool set. We will use QGIS to generate the maps and then use GIMP to animate the maps for to present the map to our potential client.

Have a feel of what an animated map is below. It is the map of edo state, Nigeria displaying various levels of details on a single GIF image file.



Animated maps are good for showing time series data. Basically, this may involves illustrating the changing of same object over time in the same area or the simultaneous movement of different objects across an area over time.

Thursday, August 23, 2018

Cartographic Map Layout Designs

Introduction:

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

Introduction:

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 EPSG.io 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.



Saturday, July 28, 2018

How to Extract Accurate Point Coordinates and Heights from Google Earth

In this post, we will use free software to extract height/elevation/altitude of points above sea level for any location in the world from DEM (digital elevation model) databases. This is fairly good data for drawing contour maps, draw a profile of a track or to colorize points by height above sea level.

The sources of the elevation data is from a DEM (digital elevation model) databases as explained below:-

DEM data sources
USGS: NED The U.S. Geological Survey's excellent National Elevation Dataset covers the United States, Canada, and Mexico. 1 arc-second (~30-meter) horizontal resolution is available in most areas (NED1). For Alaska, 60-meter data is also available (NED2). 
NASA: SRTM1 NASA's SRTM1 database (from the Space Shuttle Radar Topography Mission) has a resolution of about 30 meters. Previously, SRTM1 data was only available for the United States (and was not very useful because NED1 is generally better), but recently NASA has released SRTM1 tiles for the entire world. GPS Visualizer's server does not contain the full global dataset, but it does contain all of Europe, Japan, South Korea, and Taiwan, as well as parts of Australia, New Zealand, and South Africa. Additional locations will be installed upon request. 
ASTER: The ASTER GDEM is a joint product of NASA and the Japanese Ministry of Economy, Trade, and Industry (METI). ASTER has very good 30-meter coverage of the entire world, but the awkward download process and the massive size of the database make it impractical to store all of it on GPSVisualizer.com. ASTER files for Iceland are available, however, since none of the other 30-meter databases cover that area. (As with SRTM1 data, additional files can be added upon request.) 
NASA: SRTM3 NASA's SRTM3 dataset includes 90-meter resolution for the entire world.