geodesy and geomatics for dummies

i know how hard it is to understand things in scholarly article. so here are some of the things you need to know about geodesy and geomatics. since we are dummies, let's forget about precision and let's start to learn things randomly

[geodetwannabe]

Plotting cheatsheet - Basic Python #1

There are two things you should remember before you start plotting in Python:

1. import matplotlib.pyplot as plt --> for plotting

2. import  numpy as np --> module (tool) for array and mathematical manipulation

So, let’s say that you want to plot your data (can be points, lines, or even point on lines). Then, this is what you need:

- to plot points (scatter)

 make arrays for x and y value, then type this: pl.plot(x,y,’ro’)

or, simply put the value of x and y in the same line, e.g.: pl.plot([x1,x2,x3],[y1,y2,y3],’ro’)

the ‘ro’ in your code means that you want to make a red dot as your point. you can change it to ‘bo’ means you want to make a blue dot, or ‘g*’ means you want to plot a green star as your point.

- to plot line

make arrays for x and y value (you can change the y value with equation), then type: pl.plot(x,y)

you can also change the style of the line with added ‘--’ (e.g.: pl.plot(x,y,’r--’) if you want to have red dashed line). it works the same as point style to change the style for your lines.

- to plot multiple lines and points

just clearly have different labels for each variables (i.e. mentioned x1, y1, x2, y2, x3, etc), then plot each line and points using the same command as above. pl.plot([x1,x2],[y1,y2],’bo’) --> to plot point 1 (x1,y1) and 2 (x2,y2) pl.plot(x3,y3) --> to plot line of x3,y3 (after you define the x3 and y3)

- to plot points/line from a document

It’s a bit tricky to plot from a certain .txt file. You first need to know the format/pattern of the data. Generally, of you have a .txt data containing two components, then you can plot it as x and y in a graph. But how?

first, read your data by defining it to a certain variable (let’s say we use A to read file1 and B to read file2), by typing this:  A = np.loadtxt(’file1.txt’) B = np.loadtxt(’file2.txt’)

then, plot those data by stating this: pl.plot(np.linspace(a1,a2,a3),A) --> change the a1 with a certain number you want the axes to be start, and a2 is the end of axes. the length of your line will depends on a1 and a2, the more the difference, the longer the line. then a3 is the amount of data. A is the name of your data variable pl.plot(np.linspace(b1,b2,b3),B) --> the same as a1,a2,a3, but this works for B data. But, remember that the a3 and b3 should be the same!

Alright, now you can create graphs in Python! For more styling graphs, learn it from the linestyle section in here: https://matplotlib.org/api/lines_api.html

[geodetwannabe]

Data Processing - We should learn programming!!!

Programming is tough. I’ve tried to avoid programming, but apparently I can’t. Manual processing is just too much.

Alright, so why do you need to learn programming? Because the computer can’t read your mind, can’t listen, and can’t understand your language. So it’s YOU the who should learn the computer’s language to write down your command.

Once you master one or two programming language, then you’ll be master in data processing. As long as you know the data concept and can tell the computer what you wanna do, you can start processing anything, dude!

[geodetwannabe]

GeoTiff Compression for Dummies

“What’s the best image format for map serving?” they ask me, shortly after I tell them not to serve their images from inside a database. “Is it MrSid? Or ECW? those are nice and small.” Which indeed they are. Unfortunately, outside of proprietary image server software I’ve never seen them be fast and nice and small at the same time. Generally the decode step is incredibly CPU intensive, presum...

If any of you have a problem with huge dataset for aerial photo, read this source to compress your data using GDAL.

For me, it works by simply create a *.bat file in notepad++ of mentioned code. If you have a lot of photos, just do it in a batch file by making a list for the whole photos.

As a summary, do this following step:

1. Copy the path of the whole photos in a csv file

2. Run the whole list in *.py to make it run as a batch file in the next processing

3. Run the GDAL bat file

If you get more confuse, just compress using Adobe photoshop. xD

[geodetwannabe]

C++ Primer Plus is a carefully crafted, complete tutorial on one of the most significant and widely used programming languages today. An accessible and eas

a good resource to learn programming with c++ from a scratch

[geodetwannabe]

how to georeference a 2D data in ArcGIS? #2 (vector data)

ok, so now you have a shape file data. your goal is to stick the vector data which has a local coordinate system to a raster data in a global coordinate system.

since the georeferencing toolbar cannot be used for vector data, you have to use the spatial adjustment toolbar.

Here's the procedure:

1. open your shp file by clicking on add data

2. open your raster data as well

3. open the editor toolbar, click on start editing

5. open the spatial adjustment toolbar

6. click on new displacement link tool. pick a point in you source data (shp data), and click the same point on your reference data (raster data). you will see a line with arrow indicating that the point will be dragged on to it. do it for several points.

7. after 3 or 4 points, you can click on spatial adjustment, click set adjust data, and click all features

8. afterward, click adjust. you'll see your shapefile is already attached on the reference file!

9. to save, right click on the layer, click export data

finish!

[geodetwannabe]

how to georeference a 2D data in ArcGIS? #1 (raster data)

let say that you have a map in a local coordinate system, and you want to put it on a global coordinate system. what should you do?

1. open your data by clicking add data symbol. if you can't find your file, make sure you already create a connection folder first.

2. open the georeferencing toolbar, (click customize, point to toolbar, and click georeferencing)

3. click on add control point, pick a point as your tie point (make sure that the point can be recognized both in your data source and your reference)

4. insert coordinate of your point in the global coordinate system

5. to save changes, right click on your layer, point to data, then export data. while you exporting the data, click Data Frame (current) on spatial reference option.

Finish!

if you're not sure, just click yes on the "put a new file as a new layer?"

[geodetwannabe]

underwater photogrammetry

it's about measuring underwater objects using lens (photogrammetry technique). okay, but let us jump to the topic of the application of this underwater photogrammetry.

so, usually, this is applied for monitroing platform or pipeline, or any vital objects far far away in the ocean. according to Leatherdale & Turner (1988), three essential components for a successful operation for this, are:

1. expertise in diving and underwater photography

2. underwater camera manufacture

3. photogrammetric analysis

and, the thing we should highlight in here is, photogrammetry has been astablished as a method for underwater inspection since the 70-s. whoa!

[geodetwannabe]

how to write html? #2 (give it a style)

we knew all the basic components on how to write html. now, give it a style!

so, you need to know that we can add a comment inside the code file without making them visible in the web appearance. how? just add <!--put your comment and close with it-->

in styling, before we learn CSS, inline CSS is easier. give style=" " inside any line you want. and here are some basic stuffs you can add up inside the bracket style:

1. font-size

2. font-family

3. color

4. background-color

5. text-align

[geodetwannabe]

how to write html? #1

first thing first, the file should be saved in *.html, everything should be started with "<xxx>" and closed with "</xxx>"

- start with <html> and end with </html>

- inside, fill with heading: <head></head> and body: <body></body>

- give title for your tab in the head by adding <title></title> in heading

- give content in the body. can be formed in paragraph <p></p> or kind much of title using <h1></h1> up until <h6></h6>. h1 is the biggest font, h6 is the smallest. or, to add list, using <ol></ol>, in between, give <li></li>, for using bullet of unordered list, using <ul></ul> instead.

- to add picture, add <img src=""/>,

- to add link <a href=""></a>

to start learn to write this, check codeacademy.com

more to come later ;)

[geodetwannabe]

what is geodesy? is it something relevant with geology?

hey ya, it's quite hard to explain. yes, it is related if you mean that they have the same "geo" word. but to be exact, geodesy and geology, they have a lot of differences.

remember this:

- geo means earth.

- desy=measurement; logy=science

geodet apply mathematics and physics to identify objects on earth

geologist apply chemistry and history on earth

...

I guess so