Latest Contributions by PeterBecker

‎05-03-2016

When you add a raster dataset directly to ArcMap, by default the image layer properties are set to do standard deviation stretch based on the statistics of the raster dataset. If there are no statistics then ArcMap estimates the statistics by reading a portion of the central part of the image. In this case each image is being adjusted separately and so the difference in average is less apparent. When you add the two rasters to a mosaic dataset no stretch is applied to each individually. When the mosaic dataset is displayed a stretch is applied to the mosaic of the two images. The difference in the two images is therefore apparent. If you want the same effect, you can select the rasters and then use Batch Edit Raster functions and add a stretch to each of the rasters. (Alternatively change Raster Template when using Add Rasters). This stretch will then be applied to each raster before the images are mosaicked together.

‎11-30-2015

Strange. Not seen this before. Note that when editing the Min/MaxPS values I usually use the 'Calculate' tool to quickly set the values, which does not require start/stop editing. Two thing that come to mind that might be affecting the display, but neither really explain why the display would change when you stop editing: A) There is a 'Max Number of Rasters per Mosaic' property. This defines for each request the max number of images that will be accessed in a single request. It is possible that you have gone beyond the default of 20. The system will display the first 20, but it may appear that others are missing. Its possible that after editing you displayed a slightly different area which result in a different ordering (say if you were on closet to center) and so some image appeared to disappear. B) There is a 'Level' table that is generated that also controls which images get displayed when working with imagery of different resolutions. To check if this is causing the issue run 'Calculate Item Visibility'. In the Advanced option turn off 'Compute Min/Max Cell Sizes' (As this will reset your Min/MaxPS settings), but change the 'Cell Size Tolerance Factor' to 10. If you have images with varying pixel sizes and want them to be displayed at the same time then it is necessary to increase this value. (Its also a parameter in the MosaicDataset Properties/Default) Is the issue reproducible? How many rasters are in the current mosaic dataset. IE do you see the issue if there are larger/fewer images?

‎11-23-2015

For clarification: It is not possible to share a raster catalog as an image service. A raster catalog is only a list of raster datasets and does not have have functionality of incorporating overviews etc required to serve as the base for an image service. Use a mosaic dataset instead. If required the records from a raster catalog can be added to a mosaic dataset. Serving a mosaic dataset does require the Image Extension irrespective if you serve it directly as an image service or incorporate it into an MXD. The best practice is to serve mosaic dataset directlyu as an image service and not incorporate into an MXD so as to get the full functionality including control of the various renderers. The mashing up of the layers should be defined in a webmap and not the mxd. Authoring a mosaic dataset requires ArcGIS Desktop standard. Mosaic datasets can be used directly at any level. Raster datasets (which are single rasters) can be exported from a mosaic dataset. It is also possible to generate tile cache from a mosaic dataset. No extension is required to serve a raster dataset as an image service.

‎10-29-2015

I believe the source of your issue is an accuracy in the definition of the pixel size of the data. Looking at your graphics is would appear that the size of each raster is very slightly too small and so there is a gap between the tiles. Double check the cell size of the source data. You may find there is a rounding eg 2.667 vs 2.6666666667. After 1000 pixels the difference adds up. One way to resolve this is to create World Files for each of the MrSID files (.sdw) which are text files. Then edit the pixel size defined in them to be the correct values. Then recreate the mosaic dataset after setting (ArcMap Options, Raster, Use world file to defined the coordinates of the raster) (Don't forget to reset this afterwards) You should now find that the gaps disappear (and the issues you are facing) The gaps in the image will cause another issue in the you will get NoData values when you zoom in which will reduce performance. As Gabriel mentions you can also rebuild the footprint with a negative shrink distance.Then build the boundary and then rebuild the footprints without the negative shrink. Another solution is to use Merge. You can select set of image (a few hundred) and do a merge which will replace the rasters with a single raster. There some fixed in merge at 10.3 so I might not suggest it as a good solution in your case. Also note when creating overviews. I often find it better to use the Define Overview followed by BuildOverview. In Define overview you can define the pixel size of the initial overview. Typically I would set this to a value that is about width of typical tile/1000 and then round the number to something sensible. If then data is uniform as in this case you can set the 'Force Overview Tiles'. I also typically set the overview sampling factor to 2. (The resulting service is a bit faster, although takes a bit more space.)

‎10-15-2015

First of all, I would recommend you question if there is a need to have the imagery at the same resolution and pixel aligned. Such a process will always result in datasets being resampled. Resampling imagery by definition will decrease the quality of the imagery as you will have to interpolate a new pixel value from neighboring pixels, else get nearest neighbor sampling artifacts. One of the key capabilities of ArcGIS is that it performs such resampling on the fly. This enables the data to remain in their purest original form and only a single sampling is performed from the source to the pixels on screen, or the defined output extents and pixel size of any analysis that you perform. This handles all sorts of other changes that might occur such as reprojection with only a single controllable sampling of the pixels occuring. The additional advantages of this are that there is no additional disk space requirements and one can always refine parameters such as the georeferencing without affecting quality. If you need multiple images to be available as a single rasters you can use a mosaic dataset or if just working with a few images use the mosaic function that is part of the IAW (Image Analysis Window). Once you have a raster layer created from one or more rasters (or a mosaic dataset), if you do want to create a new raster then there are a number of options. You can either use the ‘Data/Export Data’ tool from the ‘Table of content’ and define all the parameters such as the extents and the number of rows/cols etc. The tool enables all parameters that affect the extent to be defined. Note that the resampling method used is that defined as part of the layer properties. Alternatively use Copy Raster tool, this honors the Environment variables including Extent and Snap. Again you can ensure that the output raster is pixel aligned. There are tools such as split raster that have more options on how to output the data. (Note in most cases I would recommend exporting imagery as TIF) To the question of how to update the georeferencing. Just use the georeferencing tool but use the ‘Update Georeferencing’ option. This just adds geometric transforms to the raster without changing any of the pixel values (no sampling). If you do a ‘Rectify’, this is similar to doing an Export which results in the data being resampled, but the rectify tool does not honor the environment variables. This is why I would suggest one of the above methods to persist the image. In answer to the question of order: Update georeferencing and check that the output is as required. Just use, these should be few reasons to need to export. If you do need to export use on of the methods above. Remember that best results will be obtained by not unnecessarily resampling your imagery. You will find that ArcGIS is a very ‘robust’ tool for performing all such image processing and analysis. Do rethink workflows so to remove the intermediate outputs that are typical with many of the other image processing tools.

‎09-24-2015

The USGS has a great collection of about 7Million scanned historical image. They can be searched for and available from EarthExplorer In the datasets section select on 'Aerial'. From the site you can download the images and then georeference them in ArcGIS for Desktop. We are also working to make this collection easier to access and directly use. If you are looking for Landsat data then do review the LandsatService on ArcGIS Online, they contain both new Landsat8 imagery as well as the Landsat GLS datasets going back to 1980. The services are multispectral and full resolution. If you are looking for a more a more comprehensive set of Landsat scenes then check out LandsatLook Viewer . This is based also on ArcGIS servers can one can add the same services to webmaps or ArcGIS for desktop.

‎07-27-2015

Viewpoint is a point geometry object, should have curly brackets, something like this: {"mosaicMethod" : "esriMosaicViewpoint", "viewpoint": {"x":4489798,"y":5478672,"spatialReference":{"wkid":31494}}, "ascending" : true, "mosaicOperation" : "MT_FIRST" }

‎02-20-2014

Yes. If you publish an image service then you will also see a 'Caching' tab. This enables an image service to be directly cached by the server. This is very similar to caching a feature service in that a cache of the imagery is also created. The cache can be fully created or in the advanced option there is a 'Create tiles on demand' option that causes the system to generate cached tiles only when a user first goes to an area. If an image service with a cache is added to Desktop then in the layer properties one can select if to access the cache of the dynamic image service. In web applications the app needs to define what mode to request the service in. Currently in a webmap you can not switch between the two modes.

‎02-13-2014

The cache created by server and desktop are the same. Both create by default Compact Cache that bundles the large number of JPG and PNG tiles into a smaller number of bundles. The data volume is also the same and is dependant on the levels, extent and the compresion quality (when using JPEG or Mixed). Note that even on desktop there are two differnent ways of generating the cache, either caching a Map or caching an image. If the content is image, then using the method of caching the imagery (as a single raster, raster layer or Mosaic Dataset) is preferable as it generates the cache from the highest level (smallest pixel size) first. This means that the system can generate overview by subsamling the higher resolution imagery. There was a recent Live Training Seminar on caching imagery.

‎12-17-2013

1. Bring the mosaic dataset to ArcMap, and pick the correct renderer, the on the upper right of the symbology page, save it as a function template 2. Publish the mosaic dataset as an image service, in service editor, use the function tab and provide this function template 3. Invoke the function in your client viewer. When performing identify, do not use rendering rule so you can get original values. For the single uniform block color it is posisble that the source rasters in the mosaic dataset are not accessible by the arcsoc account.

‎12-06-2013

There are various modes in recompute footprints. The Radiometry mode attempts to create a contour around the data values of the image. The system essentially creates a mask of data and no data values and then extracts the boundary. This can become very complex on some datasets. It may be that the valid data range values you are defining are incorrect resulting in no valid data values and so no contour can be generated. Try different valid data range values. The other mode is geometry. This should work and will reset the footprints to the extents of the image based on transforming the location of pixel along the edge of the image (or 4 corner pixels) to ground units. If this does not work not then the only error I can think of is that the images that you are adding are not displayable in the projection of the mosaic dataset. Best then to check by adding the rasters directly to ArcMap (after adding the mosaic dataset) to see if the image display in the correct location.

‎10-25-2013

As Michael mentions there is no real need to Cache such imagery. Caching them (or converting to prerectified tiles) actually has a number of disadvantages as it results in the imagery being flattened out and information in the overlap of the imagery is lost. The key aspect that affects storage is the scanning of the original imagery. Typically historical images are BW and scanned at resolutions of about 25um (1000dpi) on photogrammetric scanners or 40um (600dpi) for lower grade flat be scanners. Aerial Images are typically about 25x25cm. We recommend to use TIF with JPEG compression Q80 for such images. Including pyramids, the typical file size for such scans is about 12MB for 40um and 30MB for 25um. If using color imagery then use JPEG_YCBCR compression and the typical files sizes are 20MB and 50MB respectively. For some additional recommendations see the Image Management Guidebook that can be accessed through Image Management Section of the Imagery Source Center The recommended approach is to georeference the images, either using the georefercing tools in ArcGIS, else using orientation data if available and the same workflows for aerial imagery. There are many different ways to do this and the optimum depends on the number of images and accuracy required. In all cases the output should be a mosaic dataset that references the original images and defines the georeferencing and any clipping of the images. The mosaic dataset should also include the available metadata about the images so that when served as an image service users can access metadata and also control the overlap of the imagery to gain full information content. Over time as better georeferencing becomes available the mosaic dataset can just be updated. If you wanted to cache the data then this is possible. It can be done directly in ArcGIS for Desktop (see Manage Tile Cache Tool in ArcGIS 10.2) or Server. The resulting cache can be served through ArcGIS sever as a map service or packaged and uploaded and published through ArcGIS Online. Using ArcGIS Online is a very inexpensive way of serving the imagery as only low storage costs are charged. The size of the cache can be computed roughly as follows: Cache Size in Bytes is approx (Width of Extents * Height of Extents / (pixelsize^2)) / 4 Or Cache Size in MBytes is approx (Km2/pixelsize^2)/4 in MB The actual size will be dependent on compression, but this will give a rough indication. Typically what I would recommend is to do both. Serve the image service for users that want the full information content and create a cache more as a background map for general reference that can be made more widely accessible

‎07-30-2013

The issue you are seeing is related to stretches being applied to the imagery. When using an image service the server generates the view for each screen. Typically when using an image service of higher bit depth imagery, dynamic range adjustment (DRA) is turned on. This results in the server adjusting the stretch of the image dependent on the content. Areas with very dark content get lightened and visa versa. When using caching such DRA does not work well. If turned on when the cache is generated each �??super tile�?? will be generated with the appropriate stretch for that tile. This will result in borders between tiles becoming apparent as well as stretches changing from scale to scale. This is what you are seeing here. To overcome this it is necessary to turn off the DRA on the mosaic dataset prior to caching. It is necessary to fix the stretch e.g. using a min/max stretch + gamma with predefined values. Simplest is to apply a fixed stretch to each image dependent on it statistics. IE compute stats for each raster item and then apply a statistic stretch eg 0.5 percent clip. This can through be problematic when there are scenes with clouds or snow. A work around is to first mask out the clouds then compute the stretch and remove the masks. A better way to resolve this is to applying a standardized stretch that is not affected by local content, such as apparent reflectance with the atmospheric correction functions that are applied with Atmospheric Correction functions. (These have been improved at 10.2). It is then possible to provide a stretch that can be applied on all the images to make them look good. Still contrast can be lost when working on imagery with very large changed in brightness. Additionally the use of color correction can also be used to apply a stretch that changes gradually. IE first try and get the colors or the scenes to have generally good color and then apply color correction before caching. This will enable the contrast in both predominantly light and dark areas to be maintained.

‎06-14-2013

Typically this is an issue with a share and file access in that the server can access the directory that contains the overviews (stored with the geodatabase), but not the primary data. If you say this is not the case here and that any zoom in results in the display disappearing then one possibility is that the Max Size of Request (Cols,Rows) in the default properties has been set too low. Check also the values on the server. Typically the defaults are 4100,15000 which enable requests large enough for the biggest screens and plotting to be allowed, while by default stopping large exports. If these values are set small (eg 1024x1024) then you may get the case where zoomed out the image does not cover the whole screen and is within the limit, but with any zooming the image covers the whole screen and so turns off.

‎05-30-2013

Note that ECW is a proprietary format. Access to the format is controlled by Erdas, who put restrictions on the use of the format on any server technology. Erdas provide a for fee extension for ArcGIS Server to enable the serving of ECW files. This essentially licenses a GDAL driver that enables ArcGIS Server to read the format. An alternative is to convert the imagery to map cache. This can be done easily in ArcGIS 10.1 by first creating a mosaic dataset of the different images that you want (No need to create overviews). Then use the DataManagement\TileCache\ManageTileCache tool to generate a map cache. A map cache is also highly compressed although not as compact as ECW. It will generally be about 30% larger for the same quality. Such a map cache can directly be used as a raster within ArcGIS and also easily and very efficiently served through ArcGIS Server (Create a map based on a feature class that covers the extent, and use the cache in place of the map cache). Alternatively map cache can also be packaged and then shared and published through ArcGIS Online.

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Date Last Visited	‎09-30-2025 04:34 AM

My Ideas

Latest Contributions by PeterBecker

Re: Rasters in mosaic looks different then the raster itself

Re: Mosaic Dataset - rasters disappear when footprint attribute is edited

Re: How to Publish a “Raster catalog”, and is an image Server extension will be required in this case?

Re: ArcGIS 10.2.2 Mosaic Dataset -- Overviews not generated/do not display

Re: Resolution, Raster Alignment, and Georeferencing

Re: Where to find historical aerial photos?

Re: ViewPoint Mosaic Method Image Service

Re: cache raster tiles in server vs. desktop

Re: cache raster tiles in server vs. desktop

Re: Image service published from a layer file shows as block colours

Re: Adding New Imagery and updating footprint

Re: Estimating Space Needed for Caching Airphotos

Re: Image Extension for Server 10.1 not rendering image correctly at cache scales

Re: Image service disappears on zoom

Re: ecw 4 arcgis server 10.1 (2013)

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