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PCSP - Program Controlled Segmented Processing

CadnaA is able to process more than 16 million objects per object type without any problems, even models of cities. Therefore, the limiting file size is normally given by the PCs RAM. Using PCSP even this limit is irrelevant.

Using PCSP

Steps for Using PCSP

  1. Dividing a CadnaA File Using Sections (Tiles)

  2. Calculating the Model in Batch Mode. For further information, see Batch Operation.

  3. Importing / Merging results

When multiple CadnaA computers are available (e.g. in the network), all can process the same project file simultaneously, enabling parallel computation.

Generate PCSP-Tiles

Sections are used to divide the model, with each section ID following the specified pattern PART_xxx (where xxx is an increasing number with leading zeros). These sections can be created either manually or generated automatically.

Generate PCSP-Tiles automatically

Using the menu „Calculation | PCSP | Generate PCSP-Tiles“, tiles can be automatically created with the appropriate ID pattern. The following options are available for tile generation:!

Tile size

When using multiple computers and working with large CadnaA projects, the following considerations should be taken into account regarding tile size:

  • A smaller tile size results in the creation of many tiles with few receivers or grid points per tile. In batch processing, CadnaA must load, calculate, and save the file for each tile. This can significantly increase processing time, especially for large projects, as a substantial portion of the time is spent loading and saving tile by tile. Therefore, the tile size should not be set too small.
  • A larger tile size leads to fewer tiles with many receivers or grid points per tile. If fewer tiles are created than there are computers involved in the calculation, some computers will remain idle. Consequently, the tile size should not be set too large.

As a general rule of thumb, a good tile size is achieved when the number of generated tiles is approximately three times the number of computers involved in the calculation.

Consider Calculation Areas

If active, this option generates sections/tiles to include all calculation areas.

Consider Receivers / Building Evaluations

If active, this option generates sections/tiles to include all receivers / building evaluations.

Subdivide „complex“ Tiles

This option subdivides tiles depending on the specified maximum number of buildings in each tile. When the specified number of buildings is exceeded CadnaA subdivides the original tile - in the first step - into four tiles and rechecks for the criterion. When necessary these tiles are subdivided subsequently until the criterion is met. The minimum tile size (edge length) for the subdividing process of complex tiles is 100 m.

Manual generation of PCSP tiles

Tiling can also be done manually by creating, modifying, or duplicating sections. This allows for the creation of non-square tiles. For an example, refer to the Example:Manual generation of PCSP tiles.

If several CadnaA computers are at your disposal for calculation, e.g. within a network, they can simultaneously process the same project file. PCSP with its PCSP-Part-Viewer by CadnaA automatically organizes and manages the required processes.

Order of Processing when using PCSP

he individual tiles are processed according to their order in the "Section" object table, with the top entry processed first. The assigned PART number (ID of section objects in the format PART_xxx) does not affect the order of processing.

No Partial Levels when using PCSP

Displaying partial levels at receivers is not possible when using PCSP (based on tiling) as all partial levels result from different calculation runs on different computers. If partial levels are required, this is only possible in a non-PCSP calculation (batch or non-batch).

Load Tiles

After calculation, the results of individual tiles can be loaded using the menu command Calculation | PCSP | Load PCSP Tiles. The following options are available:

Dialog Load Tiles

Delete Receivers/Building Evaluation before Loading

When this option is active, building evaluations and receivers are deleted prior to import to prevent duplicate entries. If only the grid, without receivers or building evaluations, was calculated, it is recommended to deactivate this option.

Delete Tile-Files after loading

When this option is active, the calculated tile files located in the OUT folder are automatically deleted after import.

PCSP-part-viewer

The PCSP-part-viewer shows the progress of calculation by colored tiles. By this feature you receive an up-to-date information about the calculation progress, in special with large projects.

Refresh PCSP Tiles

Select from the menu Calculation|PCSP the command Refresh PCSP-tiles (alternatively, use the key combination CTRL+1.). Upon selection the predefined tiles are colorized:

  • red = unprocessed tile
  • blue = tile presently being processed
  • green = finalized tile
  • grey = calculation interrupted

The display of the calculation process is not updated automatically, but has to be engaged manually by re-selection of the command Refresh PCSP-tiles.

Displaying the processing status of the tiles

Normally, all tiles should be calculated and therefore highlighted in green. If not, additional information is available in the memo window of the respective tile (section):

Parameter Description
STATUS 0 not calculated (red)
1 calculation in process (blue)
2 calculation finalized (green)
3 calculation interrupted (gray)
COMPUTER computer’s name
TIMEBEG start of the PCSP-calculation
TIMEEND end of the PCSP-calculation
TIMESECS required calculation time of the respective tile (in seconds)

Local Textblock PCSP

During the calculation of a tiled file, CadnaA automatically creates a local text block named PCSP, which displays the processing status of the file after the calculation. The following information is available:

Parameter Description
PARTS number of tiles calculated
RADMAX search radius (m) around a tile
TIMEBEG Start of PCSP calculation (all tiles)
TIMEEND End of PCSP calculation (all tiles)

Local text block CALC_WARN

If the consistency check (see Consistency Check) shows a warning during the calculation of a tile, a local text block CALC_WARN will be created. This text block contains the warning and the tile number.

If the individual tiles are loaded back into the project after the calculation has been completed, the text blocks of each tile are copied to the local library. This serves as an overview of all warnings occurred during calculation.

Example:Manual generation of PCSP tiles

Step 1: Tiling using sections

Example

Path: Examples\Demo1.cna

  • To follow this example, open the file Demo1.cna.
  • Delete the grid (menu Grid|Delete)
  • Save the file under a different name (e.g. DemoPCSP.cna)
  • Paste a correspondingly large section - in the given example in the upper left-hand corner - in the file you would like to calculate. The section may have any desired size.
  • Subsequently, duplicate this section in a way that will cover your project file entirely and seamless. In the given example there are two horizontal sections and two vertical sections, altogether 4 sections. To this end, mark the section with the right mouse button and select the command Duplicate from the context menu. The receiver-point grid will only be calculated within the sections created this way.

First Section in this example

Settings for duplicating the section

This example file consists of 4 sections used to calculate the grid. The calculated area, however, can get even more restricted. By entering a calculation area the calculation would be restricted to the range of the calculation area inside the active tiles.

Step 2: Naming the Sections

  • Open the table Section (menu Tables|Other Objects|Section).
  • Open the table context menu by clicking on the column „ID“ with the right mouse key and select Change Column.
  • To give all sections the name „PART_“ and a consecutive numbering, enter the necessary information into the dialog box as is shown in the following picture.

Note that the word „PART_“ must be written in capitals. The two # will automatically number the section with two-digit numbers. Naming the sections is mandatory. In the given example these tiles have been given names PART_01 to PART_04.

  • Enter the desired spacing for the grid of receiver points on menu Grid|Properties. This setting will apply to all tiles.
  • Enter the corresponding settings in Calculation|Configuration. Above all, note the „Max. Search Radius“ in the „General tab“ (see step 3).

Step 3: Starting batch mode calculation

After all sections have been created and named, save the file to the corresponding IN directory. When you have tiled a file in this way, CadnaA will automatically create a second file with the file extension „Part” (e.g. DemoPCSP.cna.part). This file must also be located in the IN directory. Therefore it is easiest to save the tiled file directly in this directory because CadnaA automatically saves it in the same directory. Now, start CadnaA in the batch mode.

CadnaA now recognizes that this file is segmented. The program calculates each tile separately, taking into account not only those objects located within the tile, but also those objects located within the selected search radius. Then CadnaA saves the calculated grid in the corresponding OUT directory. These grid files have the same names as the original files and are combined with the extension of the section name but without „PART“. In our example it would be DemoPCSP.cna.01.cna, DemoPCSP.cna.02.cna (and so on).

When using several PCs in a network or a multi-processor PC, all those can calculate the tiles at the same time in parallel. CadnaA automatically organizes the distribution of the tiles to the PCs/processors available. In this case, CadnaA has to be started in batch mode on all PCs, causing all of the them accessing the IN directory.