Chapter 5 Percieving Objects and Scenes Flashcards
What is Object Recognition?
Detecting objects in an image and then matching those objects to existing stored representations of what those objects are.
Why is it so difficult to design a perceiving machine?
Overall: the mechanisms behind visual perception are remarkably complicated and not fully understood so replicating them is all but impossible
Specifically, things that make it difficult:
- The inverse projection problem
- Occlusion/hidden objects
- View Point invariance
- Blurred Objects
What is the Inverse Projection problem?
This is the task of determining the object responsible for a particular image on the retina. It is a problem because lots of 3D images cast the same 2D image on the retina. This problem is compounded when you add the fact that, due to view point variance, an object doesn’t always leave the same 2D image on the retina .
What is occlusion?
Occlusion: when objects in our visual field overlap with other objects, blocking out sections.
What is Viewpoint invariance?
Our ability to recognize objects from various viewpoints and directions.
What is perceptual organization and what are the two main processes involved?
Perceptual Organization: the process by which elements in a person’s visual field become perceptually grouped and segmented to create a perception.
Two Processes involved:
1. Grouping: the process by which elements in the visual scene are put together into coherent units or objects, putting visual events together in a way that produces meaning
- Segregation: the process of seperating one are or object from another; how we determine what things don’t go together.
These two processes work together to shape our perception.
What is Structuralism and how does it relate to Gestalt psychology?
Structuralism: sees sensation and perception as distinct processes where many sensations combine to create complex perceptions. Gestalt psychology rejects this approach
What is apparent Motion?
An illusion where something appears to move but does not actually move. It occurs when two images are flashed in separate locations with a moment of darkness between the flashes. The brain fills in the darkness with movement.
What are the 7 Gestalt Principles of Perceptual organization?
- The Principle of Good Continuation: points that, when connected, result in a straight or smoothly curving lines are seen to belong together. The lines tend to be seen in a way that follows the smoothest path. We see stimulus as continuing even when they are obscured.
- The Principle of Pragnanz: aka the principle of simplicity or of good figure. Every pattern will be seen in such a way that results in the simplest structure as possible
- The principle of similarity: similar things appear to be groups together
- The Principle of Proximity: Things that are near each other appear to be grouped together.
- Principle of Common Fate: things that move in the same direction tend to be grouped together
- Principle of Common Region: elements in the same region of space appear to be grouped together, if they are contained within the same boundary, we see them as being grouped together
- Principle of Uniform Connectedness: a connected region of the same visual properties (e.g. light, colour, texture, motion etc.) is perceived as a single unit.
What are illusory contours?
Perceiving edges that aren’t actually there.
What is figure-ground segregation? How does it relate to border ownership?
When we see a separate object, we see it as a figure that stands out against the background.
Border ownership is the idea that we see borders as belonging to the figure.
What do we use as figure cues?
Figure cues are how we decide if something is the figure. They include
- Location: areas in the lower field of vision are often perceived as the figure
- Figures are likely perceived as the convex side of borders (The bulge)
- Experience: we assign figure status to the part of the visual field that creates more meaning.
- Figures are more thing like
What is Recognition by Components Theory?
RBC theory is the idea that objects are composed of individual geometric shapes called geons and we recognize objects based on the arrangement of those geons.
This theory suggests there are 36 geons and it explains how we are able to recognize objects from different angles. It does not explain how we are able to distinguish within groups though (e.g. identifying types of birds, or different mugs)
What are the two components of a scene? How do we distinguish between objects and scenes?
A scene is a view of a real world environment that contains both a background elements AND multiple objects that are organized in a meaningful way relative to each other and the background.
Objects are acted upon, scenes are acted within.
What is the gist of a scene and how do we perceive them so quickly?
The gist of a scene is a general description of a scene that we get after only viewing the scene for a fraction of second (250ms). We perceive the gist a scene before we perceive objects and details. We use global image features to perceive the gist so quickly.
