huygen Posted June 14, 2011 Share Posted June 14, 2011 Hi, I wonder if anyone here master in drawing 3-points perspective using AutoCAD? Thanks Huygen Quote Link to comment Share on other sites More sharing options...
qball Posted June 14, 2011 Share Posted June 14, 2011 Lots of masters on here. What exactly are you trying to achieve? Quote Link to comment Share on other sites More sharing options...
huygen Posted June 15, 2011 Author Share Posted June 15, 2011 Lots of masters on here. What exactly are you trying to achieve? That's great! I would like to ask for a help. Please create a 3-points perspective drawing in AutoCAD of mine. The 3D plot will looks like the image I've attached in this reply. 3-points perspective.dwg Quote Link to comment Share on other sites More sharing options...
Bill Tillman Posted June 15, 2011 Share Posted June 15, 2011 Doing things along what you call a 3 Point Perspective, and by that I assume you're meaning X-Y-Z coordinate system or line of sight + horizon line + vanishing points...everyone has their own way of doing 3D sketches. As for this shape, I would simply layout the face view of it, PEDIT the lines and arcs to form a polyline, then EXTRUDE it to the thickness you want. That's one of the nice things about 3D drawing in AutoCAD, the complicated stuff can be left for the software to figure out for you. And like I said, there are many different ways to make this 3D shape. Your method may differ from mine but we'll end up with the same thing in the end. Quote Link to comment Share on other sites More sharing options...
qball Posted June 15, 2011 Share Posted June 15, 2011 You've already got the base shape done, so as Bill said, PEDIT > Join the arcs together, Extrude. Then use viewports in Layout Tab and the View Cube to create the perspectives you want. Quote Link to comment Share on other sites More sharing options...
SEANT Posted June 16, 2011 Share Posted June 16, 2011 (edited) Here is a perspective drawing using the vanishing point method. The arcs are simulated by degree 2 splines. Spline/Arc equivalency is achieved by setting the weight of the spline's center vertex to Cos(Included Angle/2). The other useful property of splines is that this type of transformation is automatically created with the corresponding transformation of the vertices. Perspective via VanPt.dwg Edited August 13, 2011 by SEANT Quote Link to comment Share on other sites More sharing options...
huygen Posted July 8, 2011 Author Share Posted July 8, 2011 Here is a perspective drawing using the vanishing point method. The arcs are simulated by degree 2 splines. Spline/Arc equivalency is achieved by setting the weight of the spline's center vertex to Sin(Included Angle/2). The other useful property of splines is that this type of transformation is automatically created with the corresponding transformation of the vertices. Hi Seant, Please guide me step-bystep on how to create my drawing in 3-point perspective drawing such as yours. Thank you Huygen Quote Link to comment Share on other sites More sharing options...
SEANT Posted July 13, 2011 Share Posted July 13, 2011 This may have to be a multi part demonstration. The advantage to using spline based arcs within a standard 2d drawn => 3d representation drawing is that much of the early work can use rectangles. Rectangles are fairly easy to manipulate with the standard Perspective drawing techniques. Once the Rectangles are set they can act as the SplineFrame for a degree 2 spline. The same weighting that would be applied to represent an Orthogonal spline/circular arc can be set to this modified spline frame. This process has 100% fidelity with Isometric views (see in attached). Perfect fidelity with the Perspective view would also have to transform the weighting very slightly. Given that the perspective view is generally just for visuals, that modification can be ignored. PerspectDemo.dwg Quote Link to comment Share on other sites More sharing options...
SEANT Posted August 5, 2011 Share Posted August 5, 2011 In responce to PM Here is the procedure to create a quarter circle spline arc. The quadrant can be Joined to the remaining quadrants to form a full circle, or Ellipse. PolyToSplinArc.dwg Quote Link to comment Share on other sites More sharing options...
huygen Posted August 6, 2011 Author Share Posted August 6, 2011 Can yoiu please tell me what is the next step SEANT? Quote Link to comment Share on other sites More sharing options...
SEANT Posted August 6, 2011 Share Posted August 6, 2011 Time for practice: Using the techniques shown in the files I’ve already uploaded, transfer the orthographic views onto the Isometric diagram. Practice.dwg Quote Link to comment Share on other sites More sharing options...
SEANT Posted August 6, 2011 Share Posted August 6, 2011 To illustate how to change the weight of a Control Point via the Properties Pallet. Quote Link to comment Share on other sites More sharing options...
SuperCAD Posted August 6, 2011 Share Posted August 6, 2011 If you use PRESSPULL, you may not even need to join the lines together. It should recognize the boundary and extrude the shape you want. Quote Link to comment Share on other sites More sharing options...
huygen Posted August 6, 2011 Author Share Posted August 6, 2011 http://www.cadtutor.net/forum/showthread.php?60137-3-Points-Perspective-Drawing-Using-AutoCAD&p=418961&viewfull=1#post418961Can you explain me why the value should be 0.7071? Is there any mathematical explanation on this? Is it about, for example, Bezier curve, etc.? Where I can find the mathematical theory and exercises by reading book? What book is it (title, author, publisher, etc.)? Quote Link to comment Share on other sites More sharing options...
SEANT Posted August 7, 2011 Share Posted August 7, 2011 (edited) If you use PRESSPULL, you may not even need to join the lines together. It should recognize the boundary and extrude the shape you want. A perspective via 3D would certainly be the conventional approach; this exercise, though, is more about exploring the geometries involved with the traditional 2D Perspective. Can you explain me why the value should be 0.7071? Is there any mathematical explanation on this? Is it about, for example, Bezier curve, etc.? Where I can find the mathematical theory and exercises by reading book? What book is it (title, author, publisher, etc.)? The math that forms the basis of Splines (NURB curves)forces that condition. A Weight of Cos(IncludedAngle/2). See how the weights differ in the attached drawing. Bezier Curves are a subset of NURB Curves. Beziers (and the underlying math structure) do not allow for weights other than 1. A very good resource for these types of curves can be found here: http://www.cs.mtu.edu/~shene/COURSES/cs3621/NOTES/ ThreeSplineCircs.dwg Edited August 13, 2011 by SEANT Quote Link to comment Share on other sites More sharing options...
huygen Posted August 7, 2011 Author Share Posted August 7, 2011 SEANT, can you please tell me the good geometry book, not the basic one, to learn about, I don't even know, roughly say, for example, the control point of the circle, for use in the drawing/draughting and CAD purpose? Quote Link to comment Share on other sites More sharing options...
SEANT Posted August 7, 2011 Share Posted August 7, 2011 These are good. They do require a fairly advanced knowledge of Math and math notation. http://www.amazon.com/gp/product/1558607374 http://www.amazon.com/gp/product/3540615458 http://www.amazon.com/gp/product/3540779736 Quote Link to comment Share on other sites More sharing options...
huygen Posted August 8, 2011 Author Share Posted August 8, 2011 http://www.cadtutor.net/forum/showthread.php?60137-3-Points-Perspective-Drawing-Using-AutoCAD&p=419026&viewfull=1#post419026 SEANT, can you please tell me which page from above three books so that I can obtain some informations on how to construct an ellipse inscribed in quadrilateral, in 3-point perspective drawing? Quote Link to comment Share on other sites More sharing options...
SEANT Posted August 12, 2011 Share Posted August 12, 2011 SEANT, can you please tell me which page from above three books so that I can obtain some informations on how to construct an ellipse inscribed in quadrilateral, in 3-point perspective drawing? This question was addressed via PM. huygen, have you had a chance to do the practice file in post #11 Quote Link to comment Share on other sites More sharing options...
huygen Posted August 13, 2011 Author Share Posted August 13, 2011 This question was addressed via PM. huygen, have you had a chance to do the practice file in post #11 SEANT, yes I had already doing the practice you sent me few days ago. The one that is pretty easy to me is to construct the circle-to-ellipse in isometric projection. However, the one that I feel it's so difficult to me is to construct the ellipse-to-ellipse in isometric projection. Quote Link to comment Share on other sites More sharing options...
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