Available with Advanced license.
An orthomosaic is a photogrammetrically orthorectified image product mosaicked from an image collection, where the geometric distortion has been corrected and the imagery has been color balanced to produce a seamless mosaic dataset.
The Orthomosaic wizard provides a common workflow for generating ortho image mosaics from the adjusted image collection. The Orthomosaic wizard provides a guided workflow with four preconfigured steps to generate a photogrammetrically corrected image from your image collection:
- Orthorectification
- Color balancing
- Seamline generation
- Orthomosaic settings
You can modify the default processing parameters, but you cannot remove a step. To perform a specific step, you can use the Custom wizard.
Orthorectification settings
Select the elevation source that will be used to orthorectify your mosaic.
Note:
Satellite imagery is orthorectified during adjustment using the workspace DEM. For all other workspace types, the image collection is orthorectified when generating the orthomosaic.
Parameters for Orthorectification settings
Parameter name | Description |
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Elevation Source | The digital elevation model (DEM) used to orthorectify the orthomosaic. Options include the reference DEM for the workspace, a DEM generated using the DEMs Wizard, or an external DEM. |
Color balance settings
Modify the settings to color balance your orthomosaic. Color balancing adjusts the appearance of individual images to make the transition from one image to an adjoining image appear seamless.
Parameters for color balance settings
Parameter name | Description |
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Select Mosaic Candidates | The Select Mosaic Candidates parameter is normally used for image collection with dense overlaps such as drones. It is used to find an optimum set of images that can be used in mosaicking images. The selected images will be used in seamline building, color balancing, and output mosaic operation. |
Balance Method | The color balancing algorithm to use.
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Color Surface Type | When using the Dodging balance method, each pixel needs a target color, which is determined by the surface type.
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Target Raster | The raster you want to use as a target to color balance the image collection. It can be a raster dataset, a mosaic dataset, or an image service. The statistics required by the balance method and color surface type, if applicable, will be derived from this target image. |
Recalculate Statistics | Once color balancing has been performed, there may be new pixel values within your raster. Check the check box to calculate the statistics with the latest pixel values. |
Number of Columns to Skip | The number of horizontal pixels between samples. A skip factor controls the portion of the raster that is used when calculating the statistics. The input value indicates the horizontal or vertical skip factor, where a value of 1 will use each pixel and a value of 2 will use every second pixel. The skip factor can only range from 1 to the number of columns/rows in the raster. The value must be greater than zero and less than or equal to the number of columns in the raster. The default is 1 or the last skip factor used. The skip factors for raster datasets stored in a file geodatabase or an enterprise geodatabase are different. First, if the x and y skip factors are different, the smaller skip factor will be used for both the x and y skip factors. Second, the skip factor is related to the pyramid level that most closely fits the skip factor chosen. If the skip factor value is not equal to the number of pixels in a pyramid layer, the number is rounded down to the next pyramid level, and those statistics are used. |
Number of Rows to Skip | The number of vertical pixels between samples. A skip factor controls the portion of the raster that is used when calculating the statistics. The input value indicates the horizontal or vertical skip factor, where a value of 1 will use each pixel and a value of 2 will use every second pixel. The skip factor can only range from 1 to the number of columns/rows in the raster. The value must be greater than zero and less than or equal to the number of rows in the raster. The default is 1 or the last y skip factor used. The skip factors for raster datasets stored in a file geodatabase or an enterprise geodatabase are different. First, if the x and y skip factors are different, the smaller skip factor will be used for both the x and y skip factors. Second, the skip factor is related to the pyramid level that most closely fits the skip factor chosen. If the skip factor value is not equal to the number of pixels in a pyramid layer, the number is rounded down to the next pyramid level, and those statistics are used. |
Seamline settings
Specify the seamline settings for your orthomosaic. Seamlines are polygons that are used for defining mosaicking boundaries and resolving the image overlaps.
Parameters for seamline settings
Parameter name | Description |
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Computation Method |
The computation method to use to generate your seamlines:
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Advanced Options | |
Pixel Size | The pixel size to use for seamline generation. Sometimes, a mosaic dataset contains raster items with different resolutions. This parameter allows you to choose the pixel size to use to generate your seamlines. |
Minimum Region Size | Specify the minimum region size, in pixel units. Any polygons smaller than this specified threshold will be removed in the seamline result. The default is 100 pixels. |
Processing | |
Blend Width Units |
The unit of measurement to use for blend width:
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Blend Width | Blending (feathering) occurs along a seamline between pixels where there are overlapping rasters. The blend width defines how many pixels will be blended. If the blend width value is 10, and you use BOTH as the blend type, then 5 pixels will be blended on the inside and outside of the seamline. If the value is 10, and the blend type is INSIDE, then 10 pixels will be blended on the inside of the seamline. |
Blend Type | The method for blending one image into another over the seamlines. Options are to blend inside the seamlines, outside the seamlines, or both inside and outside.
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Request Size Type | The units for the Request Size.
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Request Size | Specify the number of columns and rows for resampling. The maximum value is 5,000. Increase or decrease this value based on the complexity of your raster data. Greater image resolution provides more detail in the raster dataset but also increases the processing time. |
Sliver Removal Options | |
Minimum Thinness Ratio | Define how thin a polygon can be, before it is considered a sliver. This is based on a scale from 0 to 1.0, where a value of 0.0 represents a polygon that is almost a straight line, and a value of 1.0 represents a polygon that is a circle. Slivers are removed when building seamlines. |
Maximum Sliver Size | The maximum size a polygon can be to still be considered a sliver. This parameter is specified in pixels and is based on the Request Size, not the spatial resolution of the source raster. Any polygon that is less than the square of this value is considered a sliver. Slivers are removed when building seamlines. |
Orthomosaic settings
Specify the output settings for your mosaic.
Parameters for orthomosaic settings
Parameter name | Description |
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Pixel Size | The pixel size for the orthomosaic. |
Format | The output format for the orthomosaic:
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Compression | The compression method for the output. The following options will be available based on the Format you choose:
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