The speed is related to several factors related to the:
- Hardware used
- Graphics card
- Hard Disk
- Amount of images
- Image resolution
- Images' content
- Number of keypoints found
- If the images are geolocated or not
- Processing options selected
- Quality selected
- Amount of outputs to be generated
At the moment it is not possible to estimate how much time is left to finish a processing step.
The software is highly parallelized and takes advantage of multi-core CPUs, as well as SSE/AVX instructions and NVIDIA GPU CUDA processing. However the different steps of processing do not use these resources in the same way, and not all parts can take advantage of multi-core or CUDA. Note that to increase the performance it is important to have a balanced configuration without bottlenecks.
The CPU is the most significant component with regard to overall processing time. The CPU should be the first priority when designing a platform for processing in Pix4D. Both clock speed and number of threads have a significant impact on reducing total processing time. AMD and Intel i7, i9 CPUs both perform well under different circumstances and different models provide more value per $ than others. Gold and Platinum tier Xeon processors can perform better but cost significantly more.
Pix4Dmapper can fully utilize a single CPU per instance of the application. On systems with more than one CPU, a second project can be processed at the same time to take advantage of a second CPU. This feature would be particularly useful for large datasets that require merging. In this scenario, 2 subprojects could be processed through step 1 in parallel to save time.
The amount of RAM mostly has an impact on the number of images that can be processed in a single project. Refer to the Computer requirements article for more information.
Generally, having a combination of SSD for the OS and project processing and an HDD for data storage and project storage provides a good balance of storage and performance.
Starting with version 1.3, Pix4Dmapper takes advantage of NVIDIA GPUs with CUDA to further increase processing speed.
The benefit of processing time is almost entirely to step 1 processing. In general, a typical project can expect to have step 1 time decreased by 10%-20% depending on the image data and the processing options.
To understand what factors contribute to processing time, please review the Master hardware article. The basic factors that determine processing time are Image resolution, # of images, processing options, hardware components.
The default options of each Processing Template usually give high-quality results. Therefore, in most projects the default processing options are acceptable. The processing options should be modified in the case that:
- Different output results are required (type and format).
- Some processing options need to be adjusted to improve the quality of the results.
The main options that impact the processing speed are:
- Point cloud density/image scale
- By setting the density to low, processing will be 4 times faster. For more information: Menu Process > Processing Options... > 2. Point Cloud and Mesh > Point Cloud.
- By setting the scale to 1/4, processing will be 4 times faster. For more information: Menu Process > Processing Options... > 2. Point Cloud and Mesh > Point Cloud.
- Orthomosaic/DSM resolution
- If the GSD of a project is 4 cm, setting the number to 8 cm will produce the mosaic and DSM almost 4 times faster. For more information: Menu Process > Processing Options... > 3. DSM, Orthomosaic and Index > DSM and Orthomosaic.
Another factor that has a big impact is the number and type of outputs. By removing some outputs the processing speed increases. For the default, predefined Processing Templates, the following outputs are generated:
- Step 1. Initial Processing:
- Camera Internals and Externals, ATT, BBA.
- Automatic Tie Points.
- Quality Report.
- Step 2. Point Cloud and Mesh:
- Point Cloud (For Processing Templates: 3D Maps and 3D Models).
- 3D Textured Mesh (For Processing Templates: 3D Maps and 3D Models).
- Quality Report
- Step 3. DSM, Orthomosaic and Index:
- Raster DSM (For Processing Template: 3D Maps and 3D Maps - Rapid/Low Res).
- Orthomosaic (For Processing Template: 3D Maps and 3D Maps - Rapid/Low Res).
- Reflectance Map (For Processing Template: Ag Multispectral or Ag Modified Camera and Ag Modified Camera - Rapid/Low Res).