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| Note | ||
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Starting with version 5.2.4 of AccessMod, travel times are only given in integer numbers of minutes in all output with travel times (raster and tables). This was done to minimize the size of travel time raster files. If you specify "0" for the "maximum travel time", the maximum travel times that can be computed is actually 32'767 minutes (i.e. 22 days, 18 hours and 7 minutes), which should cover the countries in the vast majority of cases. If output travel times exceed this limit, the corresponding cell values in the output travel time raster will be encoded with |
(9) “Optimize dynamically computation according to the scenario”: this option decreases the computation time, particularly when the number of cells is large, that is when the extent of the zone is large and at high resolution. The optimisation procedure clips all raster around each facility, with clip surfaces corresponding to the maximum surface of a catchment that would be computed by using the largest speed found in the travel scenario and applied everywhere. It is not recommended to use this option if the analysis concerns all (or many) of the structures that are found all over the extent (in this case the analysis could be a bit slower).
(10) “Add short tags”: Give short tags to be attached to the different outputs of the analysis. We will use "accessibility 120" for the present exercise.
Validation:
(1011) The validation section tells you if everything is fine for you to start the analysis. First it gives you an estimation of the required memory and disk space necessary to run your analysis. Note that these estimations are indicative, and the real requirements may vary. If the memory requirements are close to the memory allocation you gave to the Virtual machine, it is a good idea to increase the latter (see Section 4.2 for how to do that). If anything is wrong in the settings, the "Compute button" will be red and a warning/error message will appear in the list, indicating errors that you will need to address prior to running the analysis. If everything is fine and all the fields have been correctly filled, a green “OK” will appear next to each item in the list and the "Compute button" will be grey (example here above). When this is the case, you can hit the button to launch the analysis.
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