Watch once
Look at the background through the plume. Opacity describes how much the plume obscures that background.
Method 9 practice: reading smoke opacity
Watch a real smoke-generator clip and practice recording opacity in 5% steps. This Method 9 practice exercise helps you learn what to look for before your official test.
Watch the sampleWhat do you see through the plume?
Choose a reading
Choose the closest value in steps of 5%: 0%, 5%, 10%, 15%, and so on, up to 100%. For example, if you estimate 12% opacity, record 10%; if you estimate 18%, record 20%. Base your estimate on how much the plume blocks the background, not on the whole video frame.
Review your approach
Which background did you use, and where did you read the plume? Replay the clip to review your approach. One still frame does not show the whole exercise.
This clip has no verified reference value, so there’s no answer or score to compare your estimate with.
What to work on during practice.
Watch how background visibility changes and get used to selecting readings in the interface. To check your accuracy, use structured exercises with known reference values.
A web sample also helps you get familiar before putting on a headset. Opacity Vision’s online lecture covers the fundamentals; your training portal provides the preparation and testing options available to you.
About this practice sample.
Can I prepare before using VR?
Yes. You can start with the online lecture and available web preparation in your training portal, then follow the instructions for your VR attempt.
Is a screenshot enough to judge my accuracy?
To check your accuracy, you need an exercise with a verified reference value and known observation conditions. A screenshot by itself does not provide that information.
Method reference: U.S. EPA Method 9. The sample above is provided by Opacity Vision.