Generate and Interpolate Point Cloud, Match Control Points, Update Interior Orientation Tools
Generate Point Cloud
How to Generate Point Cloud Tool in Arc Toolbox ArcMap ArcGIS??
 |
| Generate Point Cloud |
Path to access the tool
:
Generate
Point Cloud Tool, Ortho Mapping Toolset, Raster Box, Data Management Tools
Toolbox
Generate Point Cloud
Computes 3D points from
stereo pairs and outputs a point cloud as a set of LAS files.
The tiling of the LAS
files is based on 1,000 by 1,000 ground spacing. The points in each LAS tile
are computed by selecting pairs, based on user-defined criteria, and filter
points from the selected pairs. The input of this tool is a mosaic dataset that
contains a stereo model. The output of this tool can be used to generate a
digital terrain model (DTM) or a digital surface model (DSM).
1. Input Mosaic Dataset
The input mosaic
dataset, which must have completed the block adjustment process and have a
stereo model.
To block adjust the
mosaic dataset, use the Apply Block Adjustment tool. To build a stereo model on
the mosaic dataset, use the Build Stereo Model tool.
2. Matching Method
The method used to generate 3D points.
- ETM—A feature-based stereo matching in which the Harris operator is used in detecting feature points. Since less feature points are extracted, this method is fast and can be used for data with less terrain variations and detail.
- SGM—Semi-Global Matching (SGM) produces points that are denser and have more detailed terrain information. It can be used for images of urban areas. This is more computational intensive than ETM.1
- MVM—Multi-view image matching (MVM) is based on the SGM matching method followed by a fusion step in which the redundant depth estimations across a single stereo model are merged. It produces dense 3D points and is computationally efficient.2
References:
- Heiko Hirschmuller et al., "Memory Efficient Semi-Global Matching," ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Volume 1–3, (2012): 371–376.
- Hirschmuller, H. "Stereo Processing by Semiglobal Matching and Mutual Information." Pattern Analysis and M
3. Output LAS Folder
The folder used to store
the output LAS files.
If this tool is run
multiple times with the same input parameters, the output may be slightly
different due to random sampling.
4. Output LAS Base Name
A string used as a
prefix to formulate the output LAS file names. For example, if name is used as
the base, the output files will be named name1.las, name2.las, and so on.
5. Maximum Object Size (in meter) (optional)
A search radius within
which surface objects, such as buildings or trees, will be identified. It is
the linear size in map units.
6. DSM Ground Spacing (in meter) (optional)
The ground spacing, in
meters, at which the 3D points are generated.
The default is five
times the source image pixel size.
7. Number of Image Pairs (optional)
The number of pairs used
to generate 3D points. The default value is a minimum of 2 image pairs.
Sometimes a location may
be covered with many image pairs. In this case, the tool will order the pairs
based on the various threshold parameters specified in this tool. The pairs
with the highest scores will be used to generate the points.
8. Overlap Area Threshold (optional)
Specify a minimum
overlap threshold area that is acceptable, which is a percentage of overlap
between a pair of images. Image pairs with overlap areas smaller than this
threshold will receive a score of 0 for this criteria and will descend in the
ordered list. The range of values for the threshold is from 0 to 1. The default
threshold value is 0.6, which is equal to 60 percent.
9. Adjustment Quality Threshold (optional)
Specify the minimum
adjustment quality that is acceptable. The threshold value will be compared to
the adjustment quality value that is stored in the stereo model. Image pairs
with an adjustment quality less than the specified threshold will receive a
score of 0 for this criteria and will descend in the ordered list. The range of
values for the threshold is from 0 to 1. The default value is 0.2, which is
equal to 20 percent.
10. GSD Difference Threshold (optional)
Specify the maximum
allowable threshold for the ground sample distance (GSD) between two images in
a pair. The resolution ratio between the two images will be compared to the
threshold value. Image pairs with a ground sample ratio greater than this threshold
will receive a score of 0 for this criteria and will descend in the ordered
list. The default threshold ratio is 2.
achine Intelligence, (2008).
11. Omega/Phi Difference Threshold (optional)
Specify the maximum
threshold for the Omega\Phi difference between the two image pairs. The Omega
values and Phi values for the image pairs are compared. Image pairs with an
Omega or a Phi difference greater than this threshold will receive a score of 0
for this criteria and will descend in the ordered list.
The default threshold
difference for each comparison is 8.
Interpolate from Point Cloud
How to Interpolate from Point Cloud Tool in Arc Toolbox ArcMap ArcGIS??
 |
| Interpolate from Point Cloud |
Path to access the tool
:
Interpolate
from Point Cloud Tool, Ortho Mapping Toolset, Raster
Box, Data Management Tools Toolbox
Interpolate from Point Cloud
Interpolates a digital
terrain model (DTM) or a digital surface model (DSM) from a point cloud using
one of the provided interpolation methods.
1. Input LAS Folder or Point Table
The path and name of the
file, folder, or feature layer. The input can be a folder of LAS files or a
solution point table from orthomapping tools.
The LAS files can be the
output from the Generate Point Cloud tool, where LAS points are categorized as
ground and above ground. The solution point table is output from either the
Compute Block Adjustments tool or the Compute Camera Model tool.
2. Output Raster
The output raster
dataset location, name, and file extension.
The output can be in any
writeable raster format, such as .tif or .crf.
3. Cellsize
The cell size of the
output raster dataset.
4. Interpolation Method
The method used to interpolate the output raster dataset from the point cloud.
- TRIANGULATION— Also known as triangulated irregular network (TIN) linear interpolation designed for irregularly distributed sparse points, such as solution points from block adjustment computation.
- NATURAL_NEIGHBOR—This is similar to triangulation but generates a smoother surface and is more computationally intensive.
- IDW—This is used for regularly distributed dense points, such as point cloud LAS files from the Generate Point Cloud tool. The IDW search radius is automatically computed based on average point density.
5. Smoothing Method
Specify a filter to smooth the output raster dataset.
- GAUSS3x3—A Gaussian filter with a 3 by 3 window.
- GAUSS5x5—A Gaussian filter with a 5 by 5 window.
- GAUSS7x7—A Gaussian filter with a 7 by 7 window.
- GAUSS9x9—A Gaussian filter with a 9 by 9 window.
- NONE—Do not apply a smoothing filter.
6. Surface Type (optional)
Create a digital terrain model or a digital surface model.
- DTM—Create a digital terrain model by interpolating only the ground points.
- DSM—Create a digital surface model by interpolating all the points.
7. Input Fill DEM (optional)
A DEM raster input that
is used to fill NoData areas. Areas of NoData may exist where pixels do not
have enough information from the input to generate any values.
Match Control Points
How to Match Control Points Tool in Arc Toolbox ArcMap ArcGIS??
 |
| Match Control Points |
Path to access the tool
:
Match
Control Points Tool, Ortho Mapping Toolset, Raster
Box, Data Management Tools Toolbox
Match Control Points
Creates matching tie
points for a given ground control point and initial tie point in one of the
overlapping images.
The ortho mapping block adjustment
workflow often involves adding ground control points for a more accurate
adjustment. One ground control point is typically associated with a tie point
in each overlapping image. When there are many overlapping images for one
ground control point,
manually creating tie points for each image is labor
intensive.
1. Input Mosaic Dataset
The mosaic dataset that
contains the source imagery from which the tie points will be created.
2. Input Control Points
The input control point
set that contains a list of ground control point features and at least one
initial tie point for each ground control point.
3. Output Control Point Table
The output control point
features that contain ground control points.
4. Similarity (optional)
Specifies the similarity level for matching tie points.
- LOW—The similarity criteria for the two matching points will be low. This option will produce the most matching points, but some of the matches may have a higher level of error.
- MEDIUM—The similarity criteria for the matching points will be medium.
- HIGH—The similarity criteria for the matching points will be high. This option will produce the least number of matching points, but each matching will have a lower level of error.
Update Interior Orientation
How to Update Interior Orientation Tool in Arc Toolbox ArcMap ArcGIS??
 |
| Update Interior Orientation |
Path to access the tool
:
Update
Interior Orientation Tool, Ortho Mapping Toolset, Raster
Box, Data Management Tools Toolbox
Update Interior Orientation
Refines the interior
orientation for each image in the mosaic dataset by constructing an affine
transformation from a fiducial table.
1. Mosaic Dataset
The mosaic dataset that
is created from scanned aerial photos using the scanned raster type or frame
camera raster type.
2. Query Definition (optional)
A query definition
string that defines a subset of rasters for computing fiducials.
3. Fiducial Table (optional)
The fiducial table
created using the Compute Fiducials tool.
4. Film Coordinate System (optional)
Defines the film coordinate system of the scanned aerial photograph. It is used in computing fiducial information and affine transformation construction.
- NO_CHANGE —Maintain the coordinate system of the mosaic dataset. Do not change the film coordinate system of the scanned aerial photograph. Maintain the coordinate system of the mosaic dataset.
- X_RIGHT_Y_UP—The origin of the scanned photo's coordinate system is the center, and positive X points right and positive Y points up.
- X_UP_Y_LEFT—The origin of the scanned photo's coordinate system is the center, and positive X points up and positive Y points left.
- X_LEFT_Y_DOWN—The origin of the scanned photo's coordinate system is the center, and positive X points left and positive Y points down.
- X_DOWN_Y_RIGHT—The origin of the scanned photo's coordinate system is the center, and positive X points down and positive Y points right.
5. Update Footprints (optional)
Generates or updates the footprints of the digital photos in the mosaic dataset.
- Checked—The footprints will be generated or updated.
- Unchecked—The footprints will not be generated or updated. This is the default
Comments
Post a Comment