Mixing
Different representations for 3D objects explanation
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I'm having a hard time understanding the differences between the different representations of 3d objects following this slide (full video)
Reading the corresponding wiki pages, I can't understand the following things:
- Which one is stored as 2D images are usually stored ("classic" 2d array of 3 RGB values)
- How do the others get stored?
- I understand that Mesh is a collection of polygons, but how does it get stored as a file?
- what is the difference between volumetric and point cloud?
3d representation
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up vote
1
down vote
favorite
I'm having a hard time understanding the differences between the different representations of 3d objects following this slide (full video)
Reading the corresponding wiki pages, I can't understand the following things:
- Which one is stored as 2D images are usually stored ("classic" 2d array of 3 RGB values)
- How do the others get stored?
- I understand that Mesh is a collection of polygons, but how does it get stored as a file?
- what is the difference between volumetric and point cloud?
3d representation
edited 4 hours ago
Invariant Change
7651321
asked 4 hours ago
DsCpp
1062
New contributor
DsCpp is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
add a comment |Â
up vote
1
down vote
favorite
up vote
1
down vote
favorite
I'm having a hard time understanding the differences between the different representations of 3d objects following this slide (full video)
Reading the corresponding wiki pages, I can't understand the following things:
- Which one is stored as 2D images are usually stored ("classic" 2d array of 3 RGB values)
- How do the others get stored?
- I understand that Mesh is a collection of polygons, but how does it get stored as a file?
- what is the difference between volumetric and point cloud?
3d representation
edited 4 hours ago
Invariant Change
7651321
asked 4 hours ago
DsCpp
1062
New contributor
DsCpp is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
I'm having a hard time understanding the differences between the different representations of 3d objects following this slide (full video)
Reading the corresponding wiki pages, I can't understand the following things:
- Which one is stored as 2D images are usually stored ("classic" 2d array of 3 RGB values)
- How do the others get stored?
- I understand that Mesh is a collection of polygons, but how does it get stored as a file?
- what is the difference between volumetric and point cloud?
3d representation
3d representation
edited 4 hours ago
Invariant Change
7651321
asked 4 hours ago
DsCpp
1062
New contributor
DsCpp is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
edited 4 hours ago
Invariant Change
7651321
asked 4 hours ago
DsCpp
1062
New contributor
DsCpp is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
edited 4 hours ago
Invariant Change
7651321
edited 4 hours ago
Invariant Change
7651321
edited 4 hours ago
Invariant Change
7651321
7651321
asked 4 hours ago
DsCpp
1062
New contributor
DsCpp is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 4 hours ago
DsCpp
1062
asked 4 hours ago
DsCpp
1062
1062
New contributor
DsCpp is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
New contributor
DsCpp is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
DsCpp is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
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1 Answer
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2
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Disclaimer: not an expert
Going by your points:
- The only one of the four stored as a 2D "flat" image is the Projected View. That is the actual rendering of the 3D model in a certain projection onto a plane, which is just a normal (2D) image.
- Actual file formats can be a bit complicated and include things such as compression algorithms and metadata. To keep it cleaner, I will only address the general idea behind the aproaches.
Point Cloud you would store a list of coordinates of (as many as possible) points on the surface of your object. The more points you store, the more details you retain.
Mesh, as you said, is a list of polygons, so you would store a list of points (verices of the polygon) and then a list of lists defining which points form a polygon together. Example of a cube object (polygons are the square sides)- vertices as tuples of coordinates: 1: (0,0,0), 2: (1,0,0), 3: (0,1,0), 4: (1,1,0), 5: (0,0,1), 6:
(1,0,1), 7: (0,1,1), 8: (1,1,1), - and then the polygons as lists of vertices:
[1,2,4,3], [5,6,8,7], [1,2,6,5], [3,4,8,7], [1,5,8,4], [2,6,7,3]
- vertices as tuples of coordinates: 1: (0,0,0), 2: (1,0,0), 3: (0,1,0), 4: (1,1,0), 5: (0,0,1), 6:
volumetric I am not sre about this one, I think they might be refering to voxels. Voxels are like pixels, but 3D, so you would divide your space into small cubes and then write down coordinates of each of the cubes that is filled by the object that you try to represent (possibly even including color, opacity, material...). Again, smaller or larger voxels (cubes) provide you with more or less detail (just as less pixels show lower quality images).
Projected view see above. That is just a normal image. You can have many different projections/renderings/images from one 3D model. Generally, you cannot create the original 3D model, if all you have is a projection of it.
- See above for a small (badly formatted) example. Note that there are more ways to accomplish the same thing.
- Again, see above. They are actually quite simmilar, but the point cloud approach does not start out with a regular grid. You just use some points, not pre-determined ones. With volumetric/voxel approach, you start with a rigid (3D) grid and then you fill it in (or not) depending on what the shape is.
answered 2 hours ago
J.E
2265
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1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
up vote
2
down vote
Disclaimer: not an expert
Going by your points:
- The only one of the four stored as a 2D "flat" image is the Projected View. That is the actual rendering of the 3D model in a certain projection onto a plane, which is just a normal (2D) image.
- Actual file formats can be a bit complicated and include things such as compression algorithms and metadata. To keep it cleaner, I will only address the general idea behind the aproaches.
Point Cloud you would store a list of coordinates of (as many as possible) points on the surface of your object. The more points you store, the more details you retain.
Mesh, as you said, is a list of polygons, so you would store a list of points (verices of the polygon) and then a list of lists defining which points form a polygon together. Example of a cube object (polygons are the square sides)- vertices as tuples of coordinates: 1: (0,0,0), 2: (1,0,0), 3: (0,1,0), 4: (1,1,0), 5: (0,0,1), 6:
(1,0,1), 7: (0,1,1), 8: (1,1,1), - and then the polygons as lists of vertices:
[1,2,4,3], [5,6,8,7], [1,2,6,5], [3,4,8,7], [1,5,8,4], [2,6,7,3]
- vertices as tuples of coordinates: 1: (0,0,0), 2: (1,0,0), 3: (0,1,0), 4: (1,1,0), 5: (0,0,1), 6:
volumetric I am not sre about this one, I think they might be refering to voxels. Voxels are like pixels, but 3D, so you would divide your space into small cubes and then write down coordinates of each of the cubes that is filled by the object that you try to represent (possibly even including color, opacity, material...). Again, smaller or larger voxels (cubes) provide you with more or less detail (just as less pixels show lower quality images).
Projected view see above. That is just a normal image. You can have many different projections/renderings/images from one 3D model. Generally, you cannot create the original 3D model, if all you have is a projection of it.
- See above for a small (badly formatted) example. Note that there are more ways to accomplish the same thing.
- Again, see above. They are actually quite simmilar, but the point cloud approach does not start out with a regular grid. You just use some points, not pre-determined ones. With volumetric/voxel approach, you start with a rigid (3D) grid and then you fill it in (or not) depending on what the shape is.
answered 2 hours ago
J.E
2265
add a comment |Â
up vote
2
down vote
Disclaimer: not an expert
Going by your points:
- The only one of the four stored as a 2D "flat" image is the Projected View. That is the actual rendering of the 3D model in a certain projection onto a plane, which is just a normal (2D) image.
- Actual file formats can be a bit complicated and include things such as compression algorithms and metadata. To keep it cleaner, I will only address the general idea behind the aproaches.
Point Cloud you would store a list of coordinates of (as many as possible) points on the surface of your object. The more points you store, the more details you retain.
Mesh, as you said, is a list of polygons, so you would store a list of points (verices of the polygon) and then a list of lists defining which points form a polygon together. Example of a cube object (polygons are the square sides)- vertices as tuples of coordinates: 1: (0,0,0), 2: (1,0,0), 3: (0,1,0), 4: (1,1,0), 5: (0,0,1), 6:
(1,0,1), 7: (0,1,1), 8: (1,1,1), - and then the polygons as lists of vertices:
[1,2,4,3], [5,6,8,7], [1,2,6,5], [3,4,8,7], [1,5,8,4], [2,6,7,3]
- vertices as tuples of coordinates: 1: (0,0,0), 2: (1,0,0), 3: (0,1,0), 4: (1,1,0), 5: (0,0,1), 6:
volumetric I am not sre about this one, I think they might be refering to voxels. Voxels are like pixels, but 3D, so you would divide your space into small cubes and then write down coordinates of each of the cubes that is filled by the object that you try to represent (possibly even including color, opacity, material...). Again, smaller or larger voxels (cubes) provide you with more or less detail (just as less pixels show lower quality images).
Projected view see above. That is just a normal image. You can have many different projections/renderings/images from one 3D model. Generally, you cannot create the original 3D model, if all you have is a projection of it.
- See above for a small (badly formatted) example. Note that there are more ways to accomplish the same thing.
- Again, see above. They are actually quite simmilar, but the point cloud approach does not start out with a regular grid. You just use some points, not pre-determined ones. With volumetric/voxel approach, you start with a rigid (3D) grid and then you fill it in (or not) depending on what the shape is.
answered 2 hours ago
J.E
2265
add a comment |Â
up vote
2
down vote
up vote
2
down vote
Disclaimer: not an expert
Going by your points:
- The only one of the four stored as a 2D "flat" image is the Projected View. That is the actual rendering of the 3D model in a certain projection onto a plane, which is just a normal (2D) image.
- Actual file formats can be a bit complicated and include things such as compression algorithms and metadata. To keep it cleaner, I will only address the general idea behind the aproaches.
Point Cloud you would store a list of coordinates of (as many as possible) points on the surface of your object. The more points you store, the more details you retain.
Mesh, as you said, is a list of polygons, so you would store a list of points (verices of the polygon) and then a list of lists defining which points form a polygon together. Example of a cube object (polygons are the square sides)- vertices as tuples of coordinates: 1: (0,0,0), 2: (1,0,0), 3: (0,1,0), 4: (1,1,0), 5: (0,0,1), 6:
(1,0,1), 7: (0,1,1), 8: (1,1,1), - and then the polygons as lists of vertices:
[1,2,4,3], [5,6,8,7], [1,2,6,5], [3,4,8,7], [1,5,8,4], [2,6,7,3]
- vertices as tuples of coordinates: 1: (0,0,0), 2: (1,0,0), 3: (0,1,0), 4: (1,1,0), 5: (0,0,1), 6:
volumetric I am not sre about this one, I think they might be refering to voxels. Voxels are like pixels, but 3D, so you would divide your space into small cubes and then write down coordinates of each of the cubes that is filled by the object that you try to represent (possibly even including color, opacity, material...). Again, smaller or larger voxels (cubes) provide you with more or less detail (just as less pixels show lower quality images).
Projected view see above. That is just a normal image. You can have many different projections/renderings/images from one 3D model. Generally, you cannot create the original 3D model, if all you have is a projection of it.
- See above for a small (badly formatted) example. Note that there are more ways to accomplish the same thing.
- Again, see above. They are actually quite simmilar, but the point cloud approach does not start out with a regular grid. You just use some points, not pre-determined ones. With volumetric/voxel approach, you start with a rigid (3D) grid and then you fill it in (or not) depending on what the shape is.
answered 2 hours ago
J.E
2265
Disclaimer: not an expert
Going by your points:
- The only one of the four stored as a 2D "flat" image is the Projected View. That is the actual rendering of the 3D model in a certain projection onto a plane, which is just a normal (2D) image.
- Actual file formats can be a bit complicated and include things such as compression algorithms and metadata. To keep it cleaner, I will only address the general idea behind the aproaches.
Point Cloud you would store a list of coordinates of (as many as possible) points on the surface of your object. The more points you store, the more details you retain.
Mesh, as you said, is a list of polygons, so you would store a list of points (verices of the polygon) and then a list of lists defining which points form a polygon together. Example of a cube object (polygons are the square sides)- vertices as tuples of coordinates: 1: (0,0,0), 2: (1,0,0), 3: (0,1,0), 4: (1,1,0), 5: (0,0,1), 6:
(1,0,1), 7: (0,1,1), 8: (1,1,1), - and then the polygons as lists of vertices:
[1,2,4,3], [5,6,8,7], [1,2,6,5], [3,4,8,7], [1,5,8,4], [2,6,7,3]
- vertices as tuples of coordinates: 1: (0,0,0), 2: (1,0,0), 3: (0,1,0), 4: (1,1,0), 5: (0,0,1), 6:
volumetric I am not sre about this one, I think they might be refering to voxels. Voxels are like pixels, but 3D, so you would divide your space into small cubes and then write down coordinates of each of the cubes that is filled by the object that you try to represent (possibly even including color, opacity, material...). Again, smaller or larger voxels (cubes) provide you with more or less detail (just as less pixels show lower quality images).
Projected view see above. That is just a normal image. You can have many different projections/renderings/images from one 3D model. Generally, you cannot create the original 3D model, if all you have is a projection of it.
- See above for a small (badly formatted) example. Note that there are more ways to accomplish the same thing.
- Again, see above. They are actually quite simmilar, but the point cloud approach does not start out with a regular grid. You just use some points, not pre-determined ones. With volumetric/voxel approach, you start with a rigid (3D) grid and then you fill it in (or not) depending on what the shape is.
answered 2 hours ago
J.E
2265
answered 2 hours ago
J.E
2265
answered 2 hours ago
J.E
2265
answered 2 hours ago
J.E
2265
2265
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