Commit 09fc4422 by Kai Westerkamp

tiles

parent 5abe5541
Batch Table
JSON Header (UTF8), Binary Body
bound to tile fomats (specified , and batch lenght)
1. Array of values "name": ['name1', "name2"]
2 referenc in binary (offset, type..) -> float vec3 -> array
Feature Table
A Feature Table describes position and appearance properties for each feature in a tile. The Batch Table, on the other hand, contains per-feature application-specific metadata not necessarily used for rendering.
header + binary
Batched 3D Model .b3dm
batchLenght number of features (models)
magic - version - byteLenght - batchTableJSONByteLenght -batchTableBinaryLenght -batchLenght
batchTable, BinaryglTF
Batchtable contains model specific MetaData (styling, ..)
every vertex has a batchID (technique parameter sematic _BATCHID)
Instanced 3D Model
rendering slight variations (position ), same model with properties
inludes feature table and batch table
maps well to Opengl ANGLED instance arrays https://www.khronos.org/registry/webgl/extensions/ANGLE_instanced_arrays/
Semantics:
Position
Normal up/right
Scale
Batch_ID
x is right, y up, z forward
unreal kann in irgendeiner weise instancing
octet further reading: http://jcgt.org/published/0003/02/01/
...@@ -36,6 +36,7 @@ glTF -GL Transmission Format "JPEG for 3D" ...@@ -36,6 +36,7 @@ glTF -GL Transmission Format "JPEG for 3D"
(Animationen / skinning / bones ) (Animationen / skinning / bones )
glTF/loaders : c# threejs glTF/loaders : c# threejs
Unreal: https://github.com/RobertPoncelet/UnrealGLTFLoader Unreal: https://github.com/RobertPoncelet/UnrealGLTFLoader
binary gltf
3D tiles -> Specification for streaming massive heterogeneous 3D geospatial datasets. 3D tiles -> Specification for streaming massive heterogeneous 3D geospatial datasets.
https://github.com/AnalyticalGraphicsInc/3d-tiles https://github.com/AnalyticalGraphicsInc/3d-tiles
...@@ -61,6 +62,7 @@ glTF -GL Transmission Format "JPEG for 3D" ...@@ -61,6 +62,7 @@ glTF -GL Transmission Format "JPEG for 3D"
Precision Problems http://blogs.agi.com/insight3d/index.php/2008/09/03/precisions-precisions/ Precision Problems http://blogs.agi.com/insight3d/index.php/2008/09/03/precisions-precisions/
glTF CESIUM_RTC
Large distances, floatingpoint precision-> jittering Large distances, floatingpoint precision-> jittering
the largest number that allows approximate 1 cm increments is 131,071 (217- 1) the largest number that allows approximate 1 cm increments is 131,071 (217- 1)
\ No newline at end of file
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