PROYEKSI PIKTORIAL

SMK_edu

9 Jul 202006:17

Summary

TLDRThis video lesson discusses projection techniques, focusing on two main types: pictorial and orthogonal projections. Pictorial projection is divided into perspective, oblique, and axonometric types (isometric, dimetric, and trimetric). The video explains how objects are represented on paper with different scaling ratios based on angles and axes. It further touches on the concept of foreshortening and how to apply it when drawing in various projections. Orthogonal projection types (European and American) are introduced, but further details will be covered in the next session.

Takeaways

😀 Understanding projections: How to present a real object in a drawing.
📏 Types of projection: Divided into pictorial and orthogonal projections.
🖼️ Pictorial projection: Further divided into perspective, oblique, and axonometric projections.
🎨 Axonometric projection: Includes isometric, dimetric, and trimetric methods.
🌍 Orthogonal projection: Split into European and American methods.
🔍 Isometric projection: Uses a 30-degree angle, and the reduction scale is 1:1:1.
📐 Dimetric projection: Uses a 35-degree angle, with reduction scales of 1:3/4:1 for the X, Y, and Z axes.
🎛️ Trimetric projection: Involves different angles for X and Y axes, with unique reduction scales.
🌀 Oblique projection: Objects are angled, with reduction scales based on the tilt angle (e.g., 30, 45, 60 degrees).
👁️‍🗨️ Perspective projection: Divided into one, two, and three-point perspectives, each representing different vantage points.

Q & A

What is the definition of projection in the context of this lesson?
-Projection is the method of representing a real object in a drawing, showing how an object is presented on paper.
What are the two main types of projections mentioned in the script?
-The two main types of projections are pictorial projection and orthogonal projection.
What are the three types of pictorial projections?
-The three types of pictorial projections are perspective projection, oblique projection, and axonometric projection.
What is axonometric projection and how is it divided?
-Axonometric projection shows the edges of an object tilted relative to the projection plane, making three surfaces visible. It is divided into isometric, dimetric, and trimetric projections.
What are the differences between isometric, dimetric, and trimetric projections?
-In isometric projection, the angles between the axes are 30 degrees, and the scale reduction is 1:1:1. In dimetric projection, the angles are 35 degrees, and the scale reduction is different for each axis (1:1 for X and Z, and 3/4 for Y). In trimetric projection, the angles and scale reductions vary for all three axes.
What is the purpose of scale reduction in projections?
-Scale reduction is used to proportionally reduce the dimensions of the object along specific axes to accurately represent it in the projection.
How is scale reduction applied in dimetric projection?
-In dimetric projection, for an object with a length of 100 mm along the Y-axis, the length will be scaled by 3/4, resulting in a 75 mm representation on the Y-axis, while the X and Z axes retain their original dimensions.
What is oblique projection and how is it different from orthogonal projection?
-Oblique projection occurs when the projection is not perpendicular to the projection plane, resulting in a tilted view. Orthogonal projection involves projecting the object perpendicularly to the projection plane.
What is perspective projection and how is it categorized?
-Perspective projection focuses all projection lines toward one or more vanishing points, creating a realistic sense of depth. It is categorized into one-point, two-point, and three-point perspective, depending on how many vanishing points are used.
What will be covered in the next lesson according to the speaker?
-The next lesson will focus on orthogonal projection, as the current session only covered axonometric projection.

Outlines

00:00

🔍 Introduction to Projection Types

The speaker begins with a greeting and introduces the topic of projection, explaining it as the method of representing a real object in a drawing. The discussion covers two main types of projection: pictorial and orthogonal. Pictorial projection is further divided into perspective, oblique, and axonometric projections. Axonometric projection, in turn, includes isometric, dimetric, and trimetric forms. Orthogonal projection is divided into European and American methods. The speaker provides an overview of the distinctions between these projection types and how objects are presented on paper.

05:03

🖼️ Understanding Axonometric Projection

This section delves deeper into axonometric projection, explaining how object edges are tilted relative to the projection plane to make three surfaces visible. The speaker discusses projection angles and scale factors, starting with isometric projection, where angles and scales are equal. The dimetric projection follows, with differing angles and scale factors (X:1, Y:3/4, Z:1). The speaker also explains the principle of scale reduction, providing an example of how a 100mm length is scaled down in a dimetric projection. The focus is on the impact of angles and scaling in the representation of objects.

📐 Exploring Oblique Projection and Its Scaling

Here, the speaker explains oblique projection, where the object is not perpendicular to the projection plane, resulting in inclined angles. The speaker details how different inclination angles (30°, 45°, 60°) influence the scale reduction along the Z-axis. For example, at a 30° inclination, the scale reduction is one-third, while at 45°, it is halved. The emphasis is on understanding how different angles affect the object's representation and the application of scaling in oblique projection.

🎯 Perspective Projection and Conclusion

The final section focuses on perspective projection, where projection lines converge at a central point. The speaker outlines one-point, two-point, and three-point perspectives, each corresponding to different numbers of vanishing points, resulting in varying perspectives. The speaker concludes the lesson with a summary of axonometric projection and announces that orthogonal projection will be covered in the next session. The video ends with a closing greeting.

Mindmap

Keywords

💡Projection

Projection refers to the method of representing a three-dimensional object on a two-dimensional surface. In the video, projection is discussed as the process of illustrating a real-world object on paper. This is the central theme of the video, where different types of projection methods are explored.

💡Pictorial Projection

Pictorial projection is one of the two main types of projection discussed. It refers to a method that represents an object as it appears to the eye, showing three faces of the object simultaneously. It includes three subtypes: perspective, oblique, and axonometric projections. This type of projection gives a more realistic view of the object.

💡Axonometric Projection

Axonometric projection is a form of pictorial projection where the object is tilted so that multiple sides are visible. The video explains that it is divided into isometric, dimetric, and trimetric projections. These forms help in presenting the object without perspective distortion, making it useful for technical drawings.

💡Isometric Projection

Isometric projection is a subtype of axonometric projection where the angles between the projection axes are equal (30°), resulting in uniform scaling along each axis. The video mentions that in this projection, the scale reduction is uniform (1:1:1), which ensures the object retains proportional dimensions on all axes.

💡Dimetric Projection

Dimetric projection is another type of axonometric projection, where two axes share the same angle, but the third is different. In the video, it is explained that the reduction scale differs along the Y-axis (3/4 scale) compared to the X and Z axes. This creates a slightly distorted, but still technical, representation of the object.

💡Trimetric Projection

Trimetric projection is the third type of axonometric projection, where all three axes have different angles. The video highlights that each axis in this projection has a unique angle and reduction scale, offering more flexibility but also complexity in terms of measurements and appearance.

💡Orthogonal Projection

Orthogonal projection involves projecting an object using perpendicular lines to the projection plane. It is divided into European (first angle) and American (third angle) methods. Unlike pictorial projection, orthogonal projection focuses on precision, typically used in engineering to represent exact dimensions and views.

💡Perspective Projection

Perspective projection simulates how objects appear to the human eye, where lines converge toward a vanishing point. The video explains that this type of projection can use one, two, or three vanishing points, creating different levels of depth and realism. It is mainly used in artistic and architectural drawings.

💡Scale Reduction

Scale reduction refers to the proportional shrinking of an object’s dimensions when it is represented in a drawing. The video explains that in axonometric and oblique projections, scale reduction applies to one or more axes, depending on the projection type. For example, in dimetric projection, the Y-axis is reduced to 3/4 of its actual size.

💡Oblique Projection

Oblique projection is a type of pictorial projection where the object is presented with one face parallel to the projection plane and the other faces at an angle. The video notes that this type of projection includes different degrees of tilt, with a reduction in the Z-axis to compensate for the distortion that results from this angled view.

Highlights

Introduction to the concept of projection and its purpose in representing real objects in drawings.

Explanation of two types of projections: pictorial and orthogonal.

Pictorial projection is divided into three types: perspective, oblique, and axonometric.

Axonometric projection includes isometric, dimetric, and trimetric projections.

Orthogonal projection is divided into two types: European projection and American projection.

In axonometric projection, object edges are tilted relative to the projection plane to display three surfaces.

Isometric projection has equal foreshortening scales (1:1:1) and uses 30° angles for X and Y axes.

Dimetric projection uses 35° angles for the X and Y axes, with a foreshortening scale of 1 on the X-axis, 3/4 on the Y-axis, and 1 on the Z-axis.

Foreshortening scales adjust dimensions based on axis tilt, reducing object sizes to match the projection’s angle.

Explanation of the foreshortening scale in dimetric projection: if an object has a length of 100 mm on the Y-axis, it’s scaled down by 3/4.

Differences between isometric, dimetric, and trimetric projections are based on varying angles of the X and Y axes.

Oblique projection occurs when projection rays are not perpendicular to the projection plane, creating varying foreshortening scales on the Z-axis.

In oblique projection, foreshortening scales depend on the tilt angle, with different scales for angles of 30°, 45°, and 60°.

Perspective projection uses a single vanishing point for 1-point perspective, two points for 2-point perspective, and three points for 3-point perspective.

Conclusion: axonometric projection covered in this session, while orthogonal projection will be discussed in the next session.