Three Dimensional Display Methods
This Three Dimensional Display Methods generate a view from the solid object by projecting parallel lines onto the display plane.
By changing viewing position we can get different views of the 3D object onto the 2D display screen.
- Fig. different views object by changing viewing plane position.
- Above figure shows different views of objects.
- This technique is used in Engineering & Architecture drawing to represent an object with a set of views that maintain relative properties of the object e.g.:- orthographic projection.
This Three Dimensional Display Methods generating the view of the 3D object by projecting the point on the display plane along converging paths.
- Fig. perspective projection
- This will display object smaller when it is away from the view plane and of nearly same size when closer to the view plane.
- It will produce more realistic view as it is the way our eye is forming the image.
- Many times depth information is important so that we can identify for a particular viewing direction which are the front surfaces and which are the back surfaces of a display object.
- The simple method to do this is depth cueing in which assign higher intensity to closer object & lower intensity to the far objects.
- Depth cueing is applied by choosing maximum and minimum intensity values and a range of distance over which the intensities are to vary.
- Another application is to modeling effect of the atmosphere.
Visible line and surface Identification
- In this Three Dimensional Display Methods, we first identify visible lines or surfaces by some method.
- Then display visible lines with highlighting or with some different color.
- Another way is to display hidden lines with dashed lines or simply not display hidden lines.
- But not drawing hidden lines will lose some information.
- A similar method we can apply to the surface also by displaying shaded surface or color surface.
- Some visible surface algorithm establishes visibility pixel by pixel across the view plane. Other determines the visibility of object surface as a whole.
- A more realistic image is produced by setting surface intensity according to light reflected from that surface & the characteristics of that surface.
- It will give more intensity to the shiny surface and less to the dull surface.
- It also applies high intensity where light is more & less where light falls is less.
Exploded and Cutaway views
- Many times internal structure of the object needed to store. For ex., in machine drawing internal assembly is important.
- For displaying such views it will remove (cutaway) upper cover of a body so that internal part’s can be visible.