Tiled Images in TIFF format
- (active by default) pyramid levels contained as layers in file
- GeoTIFF tags written inside the TIFF files for georeferencing information
- (active by default) accompanying TIFF world files (*.tfw) for georeferencing information
|Depth images||32 - floating||1|
|DSM HIS (color visualization)||8 - unsigned char||3|
|DSM Image (height image)||32 - floating||1|
|DSM Quality Assessment Images (e.g. Standard Deviation, Number of Stereo Models etc)||8, 32|
|Ortho (colorized height image)||8/16 - unsigned short||1,3|
|True Ortho||8/16 - unsigned short||1,3,4|
The image products of the 2.5D workflow (DSM, True Ortho, QA layers) are written in tiled TIFF format. This means each image file is composed of smaller blocks of size 256 x 256 pixels. The tiled representation has the advantage that parts of the file can be accessed much faster without reading the whole image or reading complete rows of pixels, working with tiled TIFF therefore is less demanding on the graphics hardware and computer memory. SURE is always writing tiled TIFF images.
Image Pyramids / Overviews
The image pyramids store the tiled TIFF images at lower resolution levels and are (by default) written into the layers of TIFF files. These overviews are necessary to display efficiently extensive areas in GIS viewers, as well as when switching rapidly between different zoom levels and panning. Also in hierarchical processing through different resolutions of imagery, processes are faster as less data / lower resolutions have to be loaded for computations. The TIFF files containing these pyramids take roughly 33% more disk space than they would take without them. This option can be enabled/disabled in the project parametrization.
The GeoTIFF tags are written inside the TIFF images, storing the georeferencing information. Image viewers that don't require georeferencing information just ignore these tags, while GIS tools extract all positioning information from those tags. The writing of these tags is always active and cannot be turned off. Conventionally, the georeferencing coordinates refer to the top left corner of the top left pixel.
TIFF world files
In case the GeoTIFF tags cannot be interpreted by some GIS software, additional *.tfw files are written next to the TIFF images. Their production can be enabled/disabled in the project parametrization. By convention, the georeferencing coordinates point to the center of the top left pixel. Note that this information is consistent with the GeoTIFF tag, meaning there is an offset of half of pixel between the coordinates in the *.tfw file and the corresponding GeoTIFF tag.
"No data" convention
Images will be written with a NODATA tag. This tells the GIS software that a specific value (e.g. NaN) should be interpreted as a pixel with missing data.
Please note, that during the Dense Cloud (image matching) step the point clouds are stored in spatial 3D tiles.
While for LAS new points can be appended to existing LAS files, this is not possible for the compressed LAZ format.
Thus, one file will be created for each image related to each tile, which will be fused in the filtering and DSM step.
SURE uses the following LAS format definition: Las format definition.
|DSM Mesh / 3D Mesh||yes||no||osgb|
|DSM Mesh / 3D Mesh||no||yes||obj|
|DSM Mesh / 3D Mesh||yes||yes|
- Level-of-detail(LOD) awareness allows Web streaming of massive textured 3D mesh data. Depending on the zoom-level of the viewer, only the optimal mesh resolution for representing the visible data is loaded.
- Produce and convert to OSGB, Cesium and LOD based OBJ or Collada (*.dae) meshes e.g. for the popular Agency9's CITYPLANNER visualization solution.
Generate multiple output formats simultaneously for the Textured Meshes. See more details in Project Parametrization
- Use the stand-alone executable MeshConverter.exe or the Mesh Converter GUI to convert OSGB meshes to supported third-party formats.
Supported combinations of mesh formats ↔ texture formats:
|Mesh format||Texture format|
|obj / dae||jpg / png|
|osgb / ive||s3tc|
|cesium||s3tc / jpg|
|lod_dae / lod_ obj||jpg / png / dds|
Note that in SURE 2.2 the texturing of DSM- and 3D- Meshes has been unified. Refer to Mesh Texturing.