Latest Contributions by NeilAyres

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. ... View more

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? ... View more

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..... ... View more

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. ... View more

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? ... View more

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. ... View more

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? ... View more

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. ... View more

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. ... View more

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. ... View more

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. ... View more

So, what does the value of your variable "raster" look like in each of the loops. Perhaps examine this more carefully. ... View more

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. ... View more