7 Additional Exercises

Exercise 1: Exploring True Color (RGB) Imagery

For our first exercise, use the sheffield_cross dataset. Access the Open Drone Map sample dataset archive (https://www.opendronemap.org/odm/datasets/) to download this dataset. Create a project and select all the images as described previously. For this project, choose the Default option from the processing drop-down list. (The processing time was 43 minutes for 172 images). Follow the steps below and write your answers on a separate sheet.

• Expand the task and look at the generated orthophoto.
• Identify the features in the map and describe the general landscape type.
• Go to the Plant Health view and determine the default vegetation index chosen by the software.
• Analyze the results of this default option. Given what you know about the particular vegetation index and imagery you are working with, does it make sense? Why or why not?
• Stretch the histogram, look at the results, and describe them.
• Even if you decided the previous vegetation index was appropriate, is there one that could get better results for this image? Choose the other vegetation index we discussed and apply it.
• Stretch the histogram for the second vegetation index, look at the results, and describe them.
• Which of the two vegetation indices gives better results? Briefly explain/justify your answer.

Exercise 2: Exploring Multispectral Imagery (Altum Micasense sample imagery)

For this exercise, use the Micasense_Altum sample dataset. Download this dataset from https://tinyurl.com/DroneDataT3.

Create a project and select all the images as described previously. For this project, choose the Default option from the processing drop-down list. (The processing time was approximately 30 minutes for 197 images). Follow the steps below and write your answers on a separate sheet.

Expand the task and look at the generated orthophoto (or orthomosaic). Describe how it differs from the RGB imagery in the previous exercise.

Identify the features in the map and describe the general landscape type.

Go to the Plant Health view and determine the default vegetation index chosen by the software.

Analyze the results of this default option. Given what you know about the particular vegetation index and imagery you are working with, does it make sense? Why or why not?

Stretch the histogram, look at the results, and describe them.

Even if you decided the previous vegetation index was appropriate, is there one that could get better results for this image? Choose the other vegetation index we discussed and apply it.

Stretch the histogram for the second vegetation index, look at the results, and describe them.

Which of the two vegetation indices gives better results for this imagery? Briefly explain/justify your answer.

Exercise 3: Volumetric & Area Measurements

For this exercise, use the Dirt Pile sample dataset. Download this dataset from https://tinyurl.com/DroneDataT3.

Create a project and select all the images as described previously. For this project, choose the ‘Default’ option from the processing drop-down list. (The processing time was just approximately 30 minutes for 197 images). Follow the steps below and write your answers on a separate sheet.

• Locate the dirt pile on the image.
• Using the tools provided in WebODM, estimate the volume of dirt in the dirt pile.
• Measure the area and perimeter of the fields.