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What coordinate system is your data in? Sounds like there is a mismatch between the coordinate system (geographic degrees perhaps) and you distance. 50 in degrees is a long way. Probably need to get the data into a projected coordinate system first.
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06-19-2015
12:15 AM
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Well both tools are "resampling" the input pixels to map them to the output. Looks like you used nearest because your input looks like a binary image. Results will change depending on the input/output projection and the cell size and alignment. There is no "wrong way" really here. Did you try the anchor point options to align the outputs to an exact point?
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06-18-2015
05:19 AM
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Thanks Melita, just upgrading to 10.3.1 today. Lets hope I don't have to wait for version 12.5. I am already old.....
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06-18-2015
04:57 AM
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Jakub, you can see the default symbology for a CAD polyline is just a variant on the category above it : Unique values, many fields. In this case Linetype, Colour & Line Wt. ArcGIS just make a best guess at what colour 1, line type xx could be. I guess they are using the basic defaults for AutoCAD or Microstation. However, once exported to a proper polyline feature in an fgdb, the basic attributes are retained, Linetype etc and you can apply the same sort of categorization, but the symbology is not the same. I tried to save my CAD polyline layer symbology as a layer file, then apply it (import) to the polyline feature class, but, no nothing happens. My version 10.2.2, so yes, looks like a bug to me. Even then, I think you would still have to edit colours and what not, if you wanted the feature class to look exactly like the drawing.
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06-17-2015
09:34 AM
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Melita, this is one question that the surveyors are always beating me on the head about... Can't do height transformations. Hah! We have a bunch of vertical datums with-in the system, but then do nothing with them. If you reproject from UTMXX with vertical datum Y to the same UTM with vertical datum Z, nothing happens. Has been an issue for a while now. Say, many years. Even going from WGS84 geoidal to ellipsoid is not something that can be easily achieved. So, in amid all this development of online wizzy stuff, is anyone actually thinking about these mapping basics?
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06-17-2015
09:08 AM
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There is a Dubai Local TM defined in ArcGIS, WKID 3997. It is WGS84 based so no datum transformation is necessary. If you want to create new data in UTM 40N, add the DLTM data to a new map doc, the DF will be set to DLTM. Right click the data frame and get the properties page, coord sys. Select your UTM zone (WGS84 based). Then you can export from the TOC your data using the coord sys of the DF. Or use the Reproject tool in the tool box.
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06-17-2015
08:56 AM
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If you simply define the projection of the CAD file correctly, using the CAD properties page in Catalog. Define as your UTM zone. Does it not line up correctly then?
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06-17-2015
05:50 AM
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Well, when you add your original images into the df as shown above, are there gaps, or overlaps? If there is marginalia along the sides of the imported images, you will have to define a polygon layer as a cropping layer for the mosaic. As regards the output tiles, you could define a square polygon grid using Create Fishnet and use that to clip out square tiles.
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06-17-2015
05:45 AM
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Yes, I can see that they have different utm zones, no problem. I see that there is a projection definition for a "WGS84 Plate Carree" in the system. See here.. This map is showing the Nat Geo basemap. With the zones on top. It is a little more "stretched" east / west than a typical UTM zone. If you set up your data frame like this, then add the image tiles, everything will be reprojected into this system. No datum shift is necessary because both are WGS84 based. Then you could export them again using the coord sys of the data frame. Or try Jayanta's idea of simply importing them into a mosaic that has its coord sys already defined as WGS84 Plate Carree.
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06-17-2015
04:11 AM
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The coordinates in your table do not look like GCS (geographic) coordinates, which should be in the range XLong -180 to + 180, YLat -90 to +90. They are projected coordinates and are possibly already in UTM. You would need to confirm that with the data provider. You will also need the UTM zone (possibly also 35). If that is the case, you may not need to re-project at all, ITRF2005 is functionally equivalent to the WGS84 datum. (A geodesist might not agree with me). So, all you would need to do is define the projection correctly.
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06-17-2015
03:50 AM
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Just a comment here... Surely the data frame (initially at least) will always be oriented and aligned to the grid ie the projection. Except at the central meridian, true north (the direction of the north pole) will be slightly offset from this. Mag north varies depending on where you are. Quite a tricky problem to align the flight lines to this. Why don't they use a GPS then fly along the grid. Most survey companies do this.
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06-17-2015
03:42 AM
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What do you mean by : Can I do the inverse projection of each tile into the datum"? Then do a mosaic and then do the forward projection to Plate Carree ? A projection and the datum on which it is based are 2 entirely different issues. Re-projections from one GCS/PCS to another is easily achieved using the projection routines in ArcGIS. A datum change is a datum transformation, and will need more research depending on what is available for your data in its area of use. You have specified your output to be Plate Carree which is a worldwide pcs based on a sphere (not an ellipsoid/spheroid). Why is that? Is there not a more regional pcs that you can use. Jayanta has said that once the Mosaic is defined using your output pcs, the input rasters will automatically re-projected on-the-fly into it. Never tried that before, I have always got my inputs and outputs aligned before building the mosaic.
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06-17-2015
03:32 AM
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Not sure why this post is in the Spatial Analyst area... Have you looked at tools like Dissolve, which will aggregate data across multiple attribute columns? If you actually want a bounding box or polygon you could try Feature envelope to polygon or Minimum bounding geometry.
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06-17-2015
01:01 AM
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So, what does the value of your variable "raster" look like in each of the loops. Perhaps examine this more carefully.
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06-15-2015
02:21 AM
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There are a lot of different transformations available between ED50 & WGS84 depending on where you are in Europe and your region of use. They also have widely differing levels of accuracy. I would generally say that this is definitely a datum transformation issue, but if you have already tried all the relevant transformations and the offset is still unacceptable then perhaps you are correct to think that one or other datasets have been badly captured. How far is the offset? Are you sure about the actual coordinate system you have? Check with ArcCatalog, feature properties.
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06-15-2015
02:06 AM
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