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Hi, I am creating a map with various point and polygon layers. I need to have the layers in a projected coordinate system as I have to calculate the areas of the polygons. As such, I have projected all of the layers in the same coordinate system GDA 1994 MGA Zone 56. Once projected, however, several of my polygon layers are not aligned. The layers which were previously projected in either GDA 1994 Australian Albers, WGS 1984 ARC System Zone 10 or GCS GDA 1994 are displaying appropriately, however the layer which was projected in GCS Australian 1984 doesn't line up with the other layers. Any ideas? The geographic transformation which is being used to transform the layers from GCS Australian 1984 to GDA 1994 MGA Zone 56 is as follows: AGD_1984_To_GDA_1994_5_NTv2 Here is a screenshot of the problem [ATTACH=CONFIG]27571[/ATTACH] Thanks, Sunelle
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09-18-2013
05:28 PM
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Hi Sunelle, Assuming it isn't the result of differences in projections (and it is always wise to use the same projection when combining spatial data), there can be other reasons. Let's have a look at the help: http://resources.arcgis.com/en/help/main/10.2/index.html#//00080000000q000000 I understand that the number of points in your output point feature class is higher than the number of points in your input featureclass. Is that correct? If so, then I assume that during the spatial join your "join_operation" is set to "JOIN_ONE_TO_MANY". From the 10.2 Help: If multiple join features are found that have the same spatial relationship with a single target feature, the output feature class will contain multiple copies (records) of the target feature. For example, if a single point target feature is found within two separate polygon join features, the output feature class will contain two copies of the target feature: one record with the attributes of one polygon, and another record with the attributes of the other polygon. If you look at an input point that is found multiple times in your output and you perform an identify on your polygons, how many polygons are found at that location? If this is more than 1, your polygon feature class may contains regions (overlapping polygons). Kind regards, Xander Hi Zander, The number of points in my output point feature class in the same as my input point feature class (My join operation is set to JOIN_ONE_TO_ONE). As such, I believe it must be due to inconsistencies in projections. I have attempted to project all my layers in the same coordinate system but this doesn't seem to help. I have also changed the two layers I am joining to the same projection but the same problem occurs. The projections contained within my layers (prior to attempting projection in GDA 1994 MGA Zone 56) are as follows: GDA 1994 MGA Zone 56 GCS Australian 1984 (Polygon and Point layer) WGS 1984 ARC System Zone 10 GDA 1994 Australian Albers GCS GDA 1994 GCS WGS 1984 GDA94 - Datum (EPSG ID 6283) I have also tried to change the data frame properties to match the projection of the polygon and point layers however the same problem arises. I have checked the original attributes within the polygon layer as well to make sure that polygons only have one vegetation value assigned. Any ideas? The point should only have the attributes of the blue polygon joined, but somehow the pink polygon is also being joined. [ATTACH=CONFIG]27569[/ATTACH] Thanks, Sunelle
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09-18-2013
03:45 PM
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Hi, I am busy spatially joining the attributes from a polygon layer (regional ecosystem information) to a point layer (scat survey sites). When I complete the spatial join (join features based on polygons which the points lie completely within) I find that the attributes from multiple polygons are joined to each of the points when the point only lies within one polygon (e.g. point 1 = vegtype1(wetland) AND vegtype2(non-remnant)). I suspect this may be due to the fact that the layers have different coordinate systems. I have attempted to project the layers in one coordinate system and reduce the XY tolerance however these changes don't seem to help. Does anyone have any suggestions. Sunelle 😄
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09-17-2013
08:48 PM
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Thanks Dan and Scott for all your help. I thought there were probably spaces between the lines but I wasn't sure what to do. I will give spatial join a go and see how it goes.
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08-05-2013
02:12 PM
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I am creating a map of animal surveys and would like to get the altitude values from my elevation layer for the individual points of my survey sites using the IDENTITY tool. My elevation layer, however, is a polyline layer and as such I need to convert it to a polygon layer. I have attempted to use the FEATURE TO POLYGON tool, however, the output feature class is empty. Does anyone have any ideas?
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08-02-2013
10:52 PM
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