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What's the difference between multi-surface and composite surface?

6 years ago
October 13, 2018
4 replies
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hadhafang
14 replies

In FME what is the diffrence between composite-surface and multi-surface? As far as I can tell when reading the description they do pretty much the same thing. How do they diffrientiate and why would I use one rather then another?

Best answer by takashi

Hi @hadhafang, in my understanding, those two geometry types are different in not only internal data structure (IFMECompositeSurface and IFMEMultiSurface) also the object to represent conceptually. That is, a composite surface is a geometry that represents a continuous surface of a single object, a multi-surface is an aggregate that represents surfaces (regardless of whether those are continuous or not) of one or more objects.

For example, the surface for each individual box can be represented by either a composite surface or a multi-surface (both consisting of six Faces), but an aggregate of the surfaces of the two boxes should be represented by a multi-surface (or an aggregate), conceptually.

However, in fact, IFMECompositeSurface geometry can represent non-continuous surface too, such as the two boxes. FME internal geometry data structures are lenient to unexpected or invalid geometry data.

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takashi
7810 replies
Best Answer
6 years ago
October 13, 2018

Hi @hadhafang, in my understanding, those two geometry types are different in not only internal data structure (IFMECompositeSurface and IFMEMultiSurface) also the object to represent conceptually. That is, a composite surface is a geometry that represents a continuous surface of a single object, a multi-surface is an aggregate that represents surfaces (regardless of whether those are continuous or not) of one or more objects.

For example, the surface for each individual box can be represented by either a composite surface or a multi-surface (both consisting of six Faces), but an aggregate of the surfaces of the two boxes should be represented by a multi-surface (or an aggregate), conceptually.

However, in fact, IFMECompositeSurface geometry can represent non-continuous surface too, such as the two boxes. FME internal geometry data structures are lenient to unexpected or invalid geometry data.

be aware of unexposed but existing/exposed but not-existing attributes

+11

jovitaatsafe
Safer
635 replies
6 years ago
October 15, 2018

Hi @hadhafang,

Adding onto takashi's wonderful answer, composite surfaces also have consistent front / back directions on faces ('continuous surfaces'), which could be important for adding on textures.

Check out this webinar at about 4:00 mins to hear Dave explain the differences. Here are some more quick links to read a bit more on the topics: IFMECompositeSurface, and IFMEMultiSurface.

H

hadhafang
Author
14 replies
6 years ago
October 15, 2018

takashi wrote:

Hi @hadhafang, in my understanding, those two geometry types are different in not only internal data structure (IFMECompositeSurface and IFMEMultiSurface) also the object to represent conceptually. That is, a composite surface is a geometry that represents a continuous surface of a single object, a multi-surface is an aggregate that represents surfaces (regardless of whether those are continuous or not) of one or more objects.

For example, the surface for each individual box can be represented by either a composite surface or a multi-surface (both consisting of six Faces), but an aggregate of the surfaces of the two boxes should be represented by a multi-surface (or an aggregate), conceptually.

However, in fact, IFMECompositeSurface geometry can represent non-continuous surface too, such as the two boxes. FME internal geometry data structures are lenient to unexpected or invalid geometry data.

Thank you Takashi for an answer.

H

hadhafang
Author
14 replies
6 years ago
October 15, 2018

jovitaatsafe wrote:

Hi @hadhafang,

Adding onto takashi's wonderful answer, composite surfaces also have consistent front / back directions on faces ('continuous surfaces'), which could be important for adding on textures.

Check out this webinar at about 4:00 mins to hear Dave explain the differences. Here are some more quick links to read a bit more on the topics: IFMECompositeSurface, and IFMEMultiSurface.

Thank you @JovitaAtSafe. I've been unable finding that kind of resources

In FME what is the diffrence between composite-surface and multi-surface? As far as I can tell when reading the description they do pretty much the same thing. How do they diffrientiate and why would I use one rather then another?

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Hi @hadhafang, in my understanding, those two geometry types are different in not only internal data structure (IFMECompositeSurface and IFMEMultiSurface) also the object to represent conceptually. That is, a composite surface is a geometry that represents a continuous surface of a single object, a multi-surface is an aggregate that represents surfaces (regardless of whether those are continuous or not) of one or more objects.

For example, the surface for each individual box can be represented by either a composite surface or a multi-surface (both consisting of six Faces), but an aggregate of the surfaces of the two boxes should be represented by a multi-surface (or an aggregate), conceptually.

However, in fact, IFMECompositeSurface geometry can represent non-continuous surface too, such as the two boxes. FME internal geometry data structures are lenient to unexpected or invalid geometry data.

Hi @hadhafang,

Adding onto takashi's wonderful answer, composite surfaces also have consistent front / back directions on faces ('continuous surfaces'), which could be important for adding on textures.

Check out this webinar at about 4:00 mins to hear Dave explain the differences. Here are some more quick links to read a bit more on the topics: IFMECompositeSurface, and IFMEMultiSurface.

takashi wrote:

Hi @hadhafang, in my understanding, those two geometry types are different in not only internal data structure (IFMECompositeSurface and IFMEMultiSurface) also the object to represent conceptually. That is, a composite surface is a geometry that represents a continuous surface of a single object, a multi-surface is an aggregate that represents surfaces (regardless of whether those are continuous or not) of one or more objects.

For example, the surface for each individual box can be represented by either a composite surface or a multi-surface (both consisting of six Faces), but an aggregate of the surfaces of the two boxes should be represented by a multi-surface (or an aggregate), conceptually.

However, in fact, IFMECompositeSurface geometry can represent non-continuous surface too, such as the two boxes. FME internal geometry data structures are lenient to unexpected or invalid geometry data.

Thank you Takashi for an answer.

jovitaatsafe wrote:

Hi @hadhafang,

Adding onto takashi's wonderful answer, composite surfaces also have consistent front / back directions on faces ('continuous surfaces'), which could be important for adding on textures.

Check out this webinar at about 4:00 mins to hear Dave explain the differences. Here are some more quick links to read a bit more on the topics: IFMECompositeSurface, and IFMEMultiSurface.

Thank you @JovitaAtSafe. I've been unable finding that kind of resources