Scientific Writing - The Introduction

Well, after a long time, I thought of raising my voice- Although you may not hear the voice, you can at least read the thoughts-  creating this article, is the result. During the past few months, I was struggling endlessly to write scientific articles; I couldn't still find a way to succeed; life sure is tough. But I have gathered few important facts about scientific writing.

Scientific writing is not just presenting facts, it is about telling your story; the one you have unveiled in the research. Generally you have to tell the story systematically so that your reader is capable of grasping the main idea of the research. It is not to be forgotten that there are various readers; each and every one of them understands the story in different ways, and that is the beauty of it. For the writer however this "beauty" comes with a great pain. The writer therefore have to put the shoes of the reader and he should write so that the reader can understand what is said. One thing has to be remembered, what scientists do in researches is creating knowledge and if that knowledge can not be transferred to the common world then there is no use of doing the research. 

The scientific story starts with an "introduction"; a small briefing to the veil that is to be unveiled. In introduction, what the writers usually do is explaining the background of the study:

Lets assume that the topic of the study is "Scientific Writing", then in the introduction it is to be explained, what exactly is "Scientific Writing"; why people use it, and what kind of pros and cons are there. In many occasions the readers will find that, by reading the introduction a general picture about the whole study can be visualized, but an introduction is just a beginning; you cannot comment on the research just by reading the introduction. In an introduction, writers may explain in brief, the ongoing studies as well as the problems associated with them. 

In my brief study about the art of scientific writing, I found that the introduction is like the key to the map to the treasure of knowledge created; the knowledge which is somewhere hidden. With every word the writer is telling us what is the destination and its significance. It is the key to the map. If someone could not put the right key there at the beginning, nobody is going to find that hidden treasure- the irony is that the scientists want that treasure to be found- but it will remain hidden. 

බල්ලෝ බුරති ...!

two people make two images out of this one image... that is the  relativity of knowledge.!

සිතුම් රැළි..

අහස් ගැබ වී මගේ ලෝ තලයේ..
ස්නේහයක් පුද,
ලෝකයට රහසේ.....

සැඟව යනු කෙළෙසේ...//

ඉමක් නොපෙනෙන සිතුම් රැළි සයුරේ..
සොයා එන්නෙමි,
කෙළෙස හෝ නුඹ
ලෝකයට රහසේ...

සොයා එමි කෙළෙසේ...//

සෙනෙහසේ ක්ෂිතිජයම වී
දුර ඈත පෙනෙනා,
මා නොදන්නා ගීතය ද නුඹ
මා නොදන්නා ප්‍රේමයද නුඹ...
මගේ ලොව සරණා..
මතකයක් වී
මගේ ලොව සරණා.....//

Sensors (A & P)

hi...it has been a while that we haven't talked about our beloved topic 'remote sensing' so i thought its the time to do the otherwise.
today let us talk about sensors for a start.
in the dictionary the word 'sensor' is defined as a device which detects or measures a physical property.

well of course it is true that in the journey of our lives from birth to death we use so many sensors in order to interact with the world.in my case the world is what i have sensed through my sensors.

eyes,ears,skin,tongue,nose they all acted as sensors (but not all as remote sensors). in remote sensing we consider about the sensors which don't require a physical contact with the object being measured or detected.

the most significant sensor for me is the "EYE" it is the fundamental remote sensor of the human body.
just take a look at the human eye .

similar kind of thing happens with the sensor of a remote sensing platform.now for an eye to get info about an object light must enter through the cornea.but we all know that the source of the light which enters the eye reflecting off an object is not the eye itself, no wonder why we dont see people with flash bulb eyes lol... so human eye is what we call a "passive sensor"

passive sensors need a source to illuminate the object being observed and that source is not embedded to the sensor.(as in Landsat )

















so the active sensors are the opposite of the passive ones they have got their own source of electro-magnetic radiation emitter.(as in SONAR,LIDAR)

RS-from the Space to the "over head"

Hi, it has been a wonderful experience so far to explore some of the interesting topics in the field of remote sensing.As a matter of fact today we would jump from Satellite to the Aeroplane in order to grasp the techniques of RS...!

as we are well aware of the fact that the satellite imaging can be done with various objectives bearing in mind, i would like to summarise some of the characteristics or the abilities of some satellites(with common sense of course .... lol)

Ok, what is meant by the 2nd column header, it is simply an indication of the "spectral resolution" of the particular satellite-if it can grasp more and more bands and wavelengths the spectral resolution gets higher and higher..
Then in the next header it is named as "spatial resolution",well there is no need of big words to express what it means!!,we'll take an example mmm..
     take satellite sensor TM 4-5 (it belongs to the Landsat), it has a spatial resolution of 30m in first 5 bands,this means that the sensor can identify two objects as separate entities (or distinguish among each other ) only if the distance between them is greater than 30m !
of course by "repeat coverage" it means the temporal resolution, i'll give you a funny example,
            sri lankan A/L students can only sit for the A/L exam during the month of August,so the temporal resolution of A/L examination is (approximately) 365 days (1 year,if we count from the first day to the next first day), ***but any intelligent person may realise that not like the A/Ls the satellites do function on time so they would come to the top of a place on a sharp time....

if i dont say that by "orbit altitude" it means the height of the orbit of a particular satellite,this article would be incomplete.. but let us see what is meant by "swath width" >> !

as you can see the Swath width is the maximum distance that a sensor can grasp... if you took a rod with a length of (say) 1m and held it horizontally on a clear sand surface and dragged it,it would make a rectangle, 1m wide,similar story happens with the satellite sensor also.

Right, now lets step bit forward.

Satellite imaging is not the only possible method of taking images from above,there are so many other methods also, imagine somebody taking photographs from an aeroplane, let us not be so rude to imagine him falling to the earth .........lol.
yes, there is a methodology like that and it is called "Aerial Photogrammetry"..!
Not like in satellite imaging, in aerial photogrammetry the wavelength used to acquire information is in the visible wavelength region (most of the time.).
the reason why i put the term "most of the time" is that,in aerial photogrammetry we take photographs using a  metric (usually an analog) camera so the images are captured in their visible range.
here a Mosaic of overlapping photographs are used for the interpretation.

i would tell it like this way................
 this is identical to the act of "we flying over that terrain with our both eyes open" ,as you may have heard how we,humans see objects in a 3-dimensional way,you might witness that the way in which the photographs are taken is pretty much close to it.
the overlapping image part is in an orthogonal direction to the flight direction (side lap) must be around 30% of the swath width and the overlapping image part to the flight direction (forward lap) must be 60% of the same.in order to derive planimetric and topographic information......


let us talk about some more later. adios........!

concepts in quantitatively understanding Radiation

let us start it from where we have left.as in earlier section we figured out that the bodies/objects tend to reflect energy or spectrums of energy which are unique to them selves,having that in mind let us know about the terms such as kinetic temperature,black body,emissivity and so on..

what do we mean by "temperature" ? , well many would come up with different ideas and definitions but let us say it in this way, simply temperature is a measure of the concentration of heat, more the heat is concentrated more the temperature.

we can measure the temperature of a body made out of material by simply putting the thermometer in contact with the body,the reading we get from this is called the kinetic temperature of the particular body ( i.e. The concentration of kinetic heat of a body of material)

in a previous article we skipped the topic of blackbody radiation, so what is exactly a black body ??
     if there exists a body which is made out of a material that absorbs all the radiant energy that strikes it.then such a body/material is called a black body, not only that but also it can radiate the maximum amount of energy and this energy is dependent on the kinetic temperature.
the radiant flux of a black body is proportional to the 4th power of its kinetic temperature, and that is mathematically expressed as

here Fb is the radiant flux of the black body Tkin is the kinetic temperature and the constant s which equates the two sides is called as the Stefan-Boltzman constant, and this equation is the mathematical representation of the Stefan-Boltzman law.

we have already stated that " if there exists a body...." and so on but does there exist such a body which can be called as a black body, NO... its just an abstract physical quantity, the real objects dont behave in that manner.so we take this hypothetical black body as an indicator to express a property called emissivity of a real existing body.
the emissivity(e) is the proportion of real radiant flux to the radiant flux of the blackbody

here Fr is the radiant flux from a real material

(for more about this image and the thermal emissivity goto thermal-imaging-blog )

as you can see the value e=1 for a black body and e<1 for all real material.as we already know the objects tend to reflect certain type of radiant enery more than the others so the emissivity of a material is different when is measured at different wavelengths of radiant energy.

Radiation- Object interaction

 i have shifted my language to english as i have thought it would be convenient to relate the story in the language it was created.Ok what did i mean by the certain topic above...?

an interaction of the radiation and the object that is being observed occurs when the radiation hits the particular object (lets say "target"),thus there are three forms of interaction taking place when energy,of the radiation, strikes the object,they are;

1. absorption
2. transmission
3. reflection

by '1' we say that the incident energy (පතන ශක්තිය ) is absorbed into the target,(we cannot trace the rays after that incident)

by '2' we say that the incident ray of energy passes through the target 

by '3' we say that the radiation has been bounced back off the target in a direction opposite to the way of its initial propagation    

in remote sensing we are always interested in the number 3 category because that is what we usually measure.so let us get an understanding about the reflection phenomena.

Reflection can be divided into two different categories as,

• specular reflection-where the reflection occurs due to the incident of radiation with a smooth surface,in this particular occasion almost all the energy gets reflected in single direction 
• diffuse reflection-here the smoothness of the surface is pretty low and hence the energy is reflected almost uniformly in all possible directions      

as mentioned above the type of reflection depends on the surface roughness of the object in comparison to the wavelength of the incoming radiation.we can get it like this,

"if the incoming radiation has got shorter wavelengths than the surface variations the type of reflection would be Diffuse and Specular if it's otherwise "

ok, with that in mind lets move into the more interesting topics, we already know that the reflection occurs in almost every object(let us not be so advanced to talk about the black body radiation at this moment)

and the fact about this reflection is that it is unique to each object.thus we can identify the object using its reflection.

for an example;

tree leaves,absorbs radiation in the wavelength region in red and blue but reflects green,so we see most of the leaves as green in colour.trees would appear extremely bright
to us at these wavelengths. In fact, measuring and monitoring the near-IR reflectance is one
way that scientists can determine how healthy (or unhealthy) vegetation may be.

similarly water absorbs longer wavelengths in visible and near Infrared region but reflects more shorter wavelengths making it "blue" or "blue-green" to our naked eyes.