Mandi Assignment Analysis Procedure

VAST Challenge 2017 MC 3

Introduction

Data Preparation

Data Exploration

Final Answer

Question 1: Lake Location

As there is no sensor artifacts in the image which is taken on 2016-09-06, I take this image to locate the position of Boonsong Lake.
First, let's find out where are the waterbody in the image then we can narrow the search area.

Map B4, B3, B2 to RGB in QGIS to generate the "false-color" image.


In this band combination, water is black. Hence, we can identify the main waterbody which have been highlighted with the yellow line in the preserve area as below.

Then we zoom the image in QGIS and compare the shape of these water area with the image of Boonsong Lake. The water area appears in the left bottom corner should be the Boonsong Lake as their shape are the same. The orientation of the supplied satellite image is also the same with the image of Boonsong Lake, which is oriented north-south.

Next, let's calculate the scale of the supplied satellite image.
I load the "image09_2016_03_06.csv" into Tableau, drag X from the Measure Pane into Columns, Y from Measure Pane into Rows. Choose the Measure method as "Dimension".
As there are 651 rows and columns, I fix the range of x axis and y axis from 0 to 650. X=0, Y=0 refers to the pixel in the upper left corner of the image. Similarly, the bottom right pixel of the image is X=650, Y=650. To map the pixel in the dashboard with the real image, I reversed the scale of Y axis.

Then drag the NDVI from the Measure Pane to dashboard area and set the measure method of NDVI as "Dimension" in the Marks Card.
Choose "Square" from the drop-down list and set the size as the smallest. Then it will be easier to locate the Boonsong Lake as each square will represent one pixel.