# Unit 4 Overview

In this unit, we'll build on the material in [Unit 2 - Basics of the CoastWatch Data Analysis Tool](../Unit-2-Basics-of-the-CoastWatch-Data-Analysis-Tool/README.md), and learn about:

  - Masking out data pixels using quality variables and/or expressions
  - Showing level contours: topography and bathymetry
  - Loading line and polygon shape files
  - Saving groups of overlays for later use
  - Calculating statistics and X/Y plots for a line, rectangle, or polygon
  - Drawing shapes and text on the data view
  - Creating RGB color composite images

### Resources

For the exercises in this unit, you'll need to download the [cw_utils_sample_data.zip](../downloads/cw_utils_sample_data.zip) file that contains all the sample data for the course. Inside the ZIP file is a table of contents `00-Contents.txt` that describes all the data files — we'll use a subset of the data files in this unit.

Supplementary reading material is available in the [CoastWatch Utilities User's Guide](../downloads/cwutils_ug_4_0_0.pdf) in the following sections:

  - Section 3.5 - Displaying coastlines, grids, and more
  - Section 3.6 - Measuring distances and data statistics
  - Section 3.7 - Drawing lines, shapes, and text
  - Section 3.8 - Using composite image mode
  - Section 3.11 - User Preferences

If you prefer to learn by watching videos, there is a [YouTube playlist](https://www.youtube.com/playlist?list=PL_-bsOLKMYJybI8chOl90HWWd_jTsaO3e) for many of the same CDAT features we show and links to specific videos from the pages in this module.

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