Latest Contributions by grahamlangley-edwards

Hi, I have been using a couple mosaic datasets  of some satellite imagery for the last several months.  Yesterday I tried to zoom on the mosaics they started turning solid colors.  I have attached a screen shot for clarity.  It only happens when I zoom in past 1:1,500,000.  When I'm zoomed out beyond that some mosiacs are fine, others turn solid grey and others are combinations of solid colors.  The puzzling part is that I have been using these mosaics for months, zooming in and out with no problem, and suddenly this started happening.  The mosaic datasets have not been modified at all.  If anyone can help me out with this I would appreciate it.  Thanks, Graham ... View more

Hi, Sorry if this is not posted in the correct place, but I was not sure where to put it.  I am trying to use the Summary Statistics tool to create a summary table for a polygon layer.  In the Statistics Field drop down menu I can only select the available field headings from the layers attribute table (ID, Gridcode etc...).  However, when I make a selection I get "Error 000800 -  The value is not a member of SUM|MEAN|MIN|MAX|RANGE|STD|COUNT|FIRST|LAST".   I have tried to enter some of those values in the field manually, but I get the same error.  Seems like it is just something  I am overlooking, but  I can't figure it out.  I am using ArcGIS 10 with Windows 7 professional.  Any help is appreciated... Thanks, Graham ... View more

Hi, I have been doing supervised classifications for several Landsat images.  For the last image I classified as usual, but when I ran the classification two of the categories came up as no data.  I have included a screen shot of a the classification with no data.  I have no idea what went wrong with this classification as I followed the same work flow for all of the previous classifications, which ran fine.  I am using ArcGIS 10, and Windows 7 Professional.  If anyone has any ideas I would really appreciate the help. Thanks, Graham ... View more

Hi, I am trying to erase a portion of a raster layer using the Image Analysis windows Mask function, and then export the resulting image as a permanent layer.   I have run into 2 problems: 1. The exported image does not display the complete raster layer.  There is a portion of the bottom of the layer that does not draw.  I have included a screen shot of the temporary layer that shows the full extent, labeled "Full_Extent", of the layer.  And a screen shot of the exported layer, labeled "Not_Full_Extent",  that shows the layer with the bottom portion not drawn. I need the exported layer to fully draw.  I have  tried increasing the extent in the Environments to include an area that is much bigger than the actual layer to ensure that the extent was not the problem, but it continues to not draw the complete layer. 2.  After executing several of these types of masks, suddenly the resulting layer does not draw at all anymore.  The masked layer appears in the TOC, but does not draw.  My workflow is thus: Highlight a polygon that represents the area to be erased, select the raster layer of interest in the Image Analysis Window, Click on the Mask icon.  This creates a temporary layer in the table of contents.  Then right-click on the temporary layer and Export Data, and add the layer to the map document.  This creates a permanent layer in the TOC, but the layer does not appear in the map document. To reiterate, this workflow has been working fine, aside from the problem mentioned in 1., but then suddenly, it stopped drawing the exported layer. So I need to solve both problems, getting the permanent layer to draw at all, and getting it to draw the full extent of the layer.  I am using ArcGIS 10.  Any help is much appreciated... Thanks, Graham ... View more

Hi, I am trying to convert a raster to polygon in ArcGIS 10.  I initially used the Extract by Attributes tool to isolate elevation ranges between 1900 and 3800 meters from a 90m DEM.  I want to convert that into a polygon that I can use to clip an area of interest from some satellite tiles.  When I convert from Raster to Polygon I get a grid instead of a polygon (Screenshot2).  I also included an up close shot of the grid (Screenshot).  I'm not sure why this is happening.  The only options I have are to change the field parameter from Value to Count, but that also returns a grid structure.  How can I create a regular polygon from this data?  Any help is greatly appreciated.... Thanks, Graham ... View more

Hello, I am trying to create a contour shapefile from a mosaicked DEM using ArcGIS 10.  When I use the Contour tool in Spatial Analyst, it creates a new layer but it does not draw.  When I Zoom To Layer it zooms out to 1:120,000,000 and still nothing is drawn.  Not sure what the problem is, if anyone has any suggestions I would greatly appreciate it.  Thanks, Graham ... View more

Hi, I have a couple of Landsat 5 tiles from different dates that I am trying to mosaic together with the Create Mosaic Dataset tool.  The problem is that the tile that is displayed on top, where the two tiles overlap, changes for some reason.  It seems that the two tiles are not "sewn" together at a point where they overlap as I thought they would be, but are just displayed one on top of the other.  The one that is displayed on top changes, apparently depending on which tile is taking up the most space in arcmap at the moment.  This creates a problem because there are clouds in one of the tiles and none in the other, so the images seems to shift.  I have attached two screen shost showing the intersection of the two tiles.  The first one, North_Tile, shows the image when the cloudy northern tile is displayed on top.  The second, South_Tile, shows the cloud free southern tile displayed on top.  In the left corner where they intersect you can see a cloud in the first tile and no cloud in the second tile.   Is there a way to get the tiles to fuse together into one image with the north tile on top? Also, I would like to create a more seamless image.  The seam is rather obvious and contains black pixels, shown in the Seamline screen shot attached.  I have already color corrected, the Default Mosaic Method is Seamlines, the Default Mosaic Operator is Max.   So, is there a way to create a more seamless image? Some info on the images:  Pixel type: unsigned integer Pixel Depth: 8 bit Format: AMD Number of Bands: 7 Any help is greatly appreciated... Regards, Graham ... View more