Toolbox : Multiresolution Maker

Use this tool to convert large images to a Multiresolution format. By converting to multiresolution, access to the imagery is improved dramatically.

This tool provides in 3 native Orbit techniques : Flat OID, MR OID, OMI

OID or 'Orbit Image Database' makes an index of a series of image files. For example: you have a large area covered by a set of tiled images. Each image covers just a piece and the set covers your area of interest. You can easily view each image file separately, but it is much more effective to combine all images of the set in one image database or OID file, and let Orbit do the work for you.

Select a directory with all your images and create an OID file. The OID file will index the images. Orbit GIS can open an OID file and will display the proper images on the proper spot. Do take care of the size. If you zoom out and require Orbit GIS to render all images, this may take a while if you do not have multiresolution imagery available. If this is the case, you might consider the MR OID or OMI formats.

Note : OID does not alter the original image files, it just creates an index.

This OID format will not only create the index of imagery as the Flat OID format does, but also create a pyramid of multiresolution imagery. These image files combine all source images in sets of decreasing resolution, so that finally the last image is a single low resolution image covering the whole project. The images are stored in subfolders and are georeferenced. You ca choose in which format the MR-images are stored and you can use them separately.

When Orbit uses the MR OID format, fast access to vast amounts of imagery is guaranteed.

The OMI or Orbit Multiresolution Image is a single compressed multiresolution image format using orbit compression technology. It does behave similar to other multiresolution image formats (such as MR OID, ECW or MrSID) but does not use wavelet compression. The compression factor is about 2,5 less than wavelet compression.

Why use OMI ? OMI is a single file, which makes it easy to handle. OMI can also compress black and white imagery (which wavelet compression cannot) and is portable from Windows, Linux, Mac, Unix etc.

Open the Toolbox

• From menu: Tools<Toolbox…<Image<Multiresolution maker

Choose from 3 types of source data :

• A Directory with image files that form a single project. The tool will scan for all recognisable image files.
• An existing OID file. Use this to convert a Flat OID to an MR OID or OMI. You can also choose to delete this file afterwards.
• A single image file to create MR OID or OMI from.

Define a target file folder and file name. Then choose the file type.

• MR OID
  This will create and *.OID file with the given filename, will contain references to the images set in the Source panel, and will create mr-subfolders in the same folder as the target OID file. The mr-subfolders will be named mr1, mr2, mr3, … up to a single image remains. MR OID will not alter the source images in any way, nor make copies of them or compress them. It is advised to keep source and target files together. This may take quite some time.
• Flat OID
  this will create and *.OID file with the given filename, and will contain references to the images set in the Source panel. Flat OID will not alter the source images in any way, nor make copies of them or compress them. It is advised to keep source and target files together.
• OMI
  This will create a single *.OMI file with the given name. OMI will copy and compress all source images, and create mr-folders in one go and combine all this imagery in a single file. This may take quite some time and will require disc space.

When choosing MR OID or OMI, you can specify multiresolution settings.

The MR OID type allows you to choose the format in which the multiresolution image tiles will be created, as well as their size and resample factor. The size specifies exactly the amount of pixels for each tiled. The resample factor sets the difference in resolution between two resolution layers. The larger this factor, the less image disc space will be required, but you will increasingly see differences in the image resolution layers when zooming.

When all parameters are set, click Go. MR OID and OMI may take quite some time, so run this tool carefully. The progress bar gives you some indication.