Question

clipper result not as expected

boubcher
Rank
Badge +10

Hello There I have 2 polygons, as you can see on the inspector both are into different location

all using projected coordinate when we using the clipper it inside results

how this is possible

10 replies

danilo_fme
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Userlevel 4
Badge +30

Hi @boubcher

I saw that the Reader Parcel.shp has the coordinate UTM84-37N and the other Source Boundary.shp has the coordinate UTM84-38N.

When I executed the Workspace the Source data:

The LOg File Inspector show this about the coordinate system predefined in FME Data Inspector:

The Result of Clipper Transformer:

Thanks,

Danilo

boubcher
Rank
Badge +10

Hi @boubcher

I saw that the Reader Parcel.shp has the coordinate UTM84-37N and the other Source Boundary.shp has the coordinate UTM84-38N.

When I executed the Workspace the Source data:

The LOg File Inspector show this about the coordinate system predefined in FME Data Inspector:

The Result of Clipper Transformer:

Thanks,

Danilo

@danilo_fme

 

then the clipper is right and the problem is the viewer ? showing the parcle into the wrong place ?
boubcher
Rank
Badge +10

Hi @boubcher

I saw that the Reader Parcel.shp has the coordinate UTM84-37N and the other Source Boundary.shp has the coordinate UTM84-38N.

When I executed the Workspace the Source data:

The LOg File Inspector show this about the coordinate system predefined in FME Data Inspector:

The Result of Clipper Transformer:

Thanks,

Danilo

 

@danilo_fme

 

when you add a bing background Map , then the pacel is completely out side could you explain

 

Thanks
danilo_fme
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Userlevel 4
Badge +30

 

@danilo_fme

 

when you add a bing background Map , then the pacel is completely out side could you explain

 

Thanks
Hi,

 

I generated a Writer KML and the result in Google Earth:

 

 

 

 

takashi
Rank
Userlevel 2
Badge +17

Hi @boubcher, as @danilo_fme mentioned, the parcel and the boundary have different coordinate systems.

If the coordinate systems defined in the datasets are correct, those geometries don't intersect geographically. However, the Clipper just treats input features as geometric shapes without considering their coordinate systems, so the boundary would be clipped by the parcel. I think that's the situation you have observed.

If you need to perform clipping operation correctly according to geographic spatial relations, you will have to reproject the features into the same coordinate system beforehand.

boubcher
Rank
Badge +10

Hi @boubcher, as @danilo_fme mentioned, the parcel and the boundary have different coordinate systems.

If the coordinate systems defined in the datasets are correct, those geometries don't intersect geographically. However, the Clipper just treats input features as geometric shapes without considering their coordinate systems, so the boundary would be clipped by the parcel. I think that's the situation you have observed.

If you need to perform clipping operation correctly according to geographic spatial relations, you will have to reproject the features into the same coordinate system beforehand.

@takashi

 

both are in a projected coordinate system one is in zoon 37 and other 38 ,

 

to get accurate result cliping opration should be done on project object , and this is our case

 

am I missing anything ?
takashi
Rank
Userlevel 2
Badge +17

Hi @boubcher, as @danilo_fme mentioned, the parcel and the boundary have different coordinate systems.

If the coordinate systems defined in the datasets are correct, those geometries don't intersect geographically. However, the Clipper just treats input features as geometric shapes without considering their coordinate systems, so the boundary would be clipped by the parcel. I think that's the situation you have observed.

If you need to perform clipping operation correctly according to geographic spatial relations, you will have to reproject the features into the same coordinate system beforehand.

Since those are different zones, naturally the Clipper cannot perform geographically correct clipping operation. You need reproject them onto the same coordinate system before clipping.

 

 

danilo_fme
Rank
Userlevel 4
Badge +30
@takashi

 

both are in a projected coordinate system one is in zoon 37 and other 38 ,

 

to get accurate result cliping opration should be done on project object , and this is our case

 

am I missing anything ?
Just completing that @takashi

 

mentioned here in Brazil for example We have region with 3 different zones in the same State. In this project we reproject these 3 zones for the same coordinate system.

 

boubcher
Rank
Badge +10

Hi @boubcher, as @danilo_fme mentioned, the parcel and the boundary have different coordinate systems.

If the coordinate systems defined in the datasets are correct, those geometries don't intersect geographically. However, the Clipper just treats input features as geometric shapes without considering their coordinate systems, so the boundary would be clipped by the parcel. I think that's the situation you have observed.

If you need to perform clipping operation correctly according to geographic spatial relations, you will have to reproject the features into the same coordinate system beforehand.

 

@takashi

 

if you remove the background Map, both will even with 2 diffrent projected coordinate overlap, and in the reel world they overlap

 

but when you add the background map, the parcel is not in the same place

 

if its projection problem the should not overlay even when we remove the background map

 

just trying to understand why is that

 

takashi
Rank
Userlevel 2
Badge +17

Hi @boubcher, as @danilo_fme mentioned, the parcel and the boundary have different coordinate systems.

If the coordinate systems defined in the datasets are correct, those geometries don't intersect geographically. However, the Clipper just treats input features as geometric shapes without considering their coordinate systems, so the boundary would be clipped by the parcel. I think that's the situation you have observed.

If you need to perform clipping operation correctly according to geographic spatial relations, you will have to reproject the features into the same coordinate system beforehand.

data inspector with background map reprojects features onto the same coordinate system. If those two features are overlap in the real world, the coordinate system defined in the dataset could be wrong.

 

 

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