How to create a irregular solid from coordinates and know its volume.??????

[jcaz15]

Hi, everybody, I am doing my thesis about a theory which uses som vectorial methods in rock mechanics to know the volume of a block that could fall.... I know how to get the coordinates edges of this blocks, but I would like to draw them in autocad and then try to get some basic properties, to prove my hand calculations, but I was triying using a 3dpoly to construct the block, which I was able, but I didn´t how to take the volume.

 

How can I do it, it would be better if the final product is a solid which a can render or something like that.

 

In a example i will use this data... they are the the edge vector that define the block in other words the point that need to be "join".

 

a= (0.89442, 0.16368,0.37720)

b=(0.46182, 0.53790, -0.096664)

c= (0.76232, -0.24092, -0.12500)

d=(0 , 0 , 0)

 

Thank you a lot.

[fuccaro]

As you can see in my profile, I use AutoCAD 2006. The solid modelling changed alot starting with AutoCAD 2007, so I may be wrong.

Using 3Dpolylines you can create only the wiraframe, not the solid itself. An approach could be to draw a box or a sphere that contains your points. Now use four times the SLICE command. First time indicate a,b and c as points to define the slicing plane and d as point on the desired part. Restart the command and indicate a,b and d to define the plane and c to indicate the desired part. The third section planne could be acd and the fourth: bcd.

For a lot of "blocks" I would try to use a Lisp routine to draw them for me.

[shift1313]

im assuming when you make these statements you decide the "sides" are straight lines between these points and not some sort of jagged edge? The coordinates you gave above gives a pyramid. Is there going to be some sort of convention with your vectors, like are all objects going to be the product of 3 planes? Or will you have the possibility of an object with more than 4 planar surfaces?

 

Massprop works if you have a solid, but you need to convert your surface to solid in some method. If all of your "objects" will have the same general shape it probably wouldnt be a stretch to write an autolisp routine that starts with a block and creates slices through your vectors.

 

sorry i dont have a quick and easy answer for you.

[jcaz15]

Hi, again, thank your the advices, the method given by fuccaro, works, but it´s a little boring if you have to do it for a lot of blocks....... In my case it is just for test my hand calculations, thats all, so the method its ok... but if someone know other easier method, welcome..

 

Tx shift1313 too.

[fuccaro]

There is a way to sped up a little bit your work. First of all create points (using the POINT command) at the coords of a,b,c and d. Now start the slice command and just pick the desired points with your mouse. The NEAR osnap mode must be active.

I could write the lisp for you. By chance, are the point's coords stored in a file? if so, in what format? Or maybe you will enter numbers from your keybord?