[BlenderBIM & CharonIFC] Construction Project Planning, and Cost Scheduling

M by Moult on 3 Jun 2021, edited 3 Jun 2021 # +7 votes

@brunopostle indeed I was using networkx, and using their in-built algorithms.

The good news is that the code has been now rewritten and optimised, thanks to @SigmaDimensions who pointed out another video showing another method of doing the calcs by hand (which is much simpler than the method I saw taught in another YouTube tutorial! That's why we need domain experts!). This method is much faster which is O(n²) in the worst case, where n is the number of tasks. With 500 tasks, it is now calculated in under a second, so as far as I'm concerned, this is a huge win. In theory, the new approach may not even require networkx since we no longer use any of their algorithms, but there is still a bit of work to do before this is finished, so we'll wait and see.

Things still to do:

Take into account different calendars during float and early / late date calculations and resolve durations into dates
Calculate free float
Do an incremental calculation (i.e. if you only change one task)

M by Moult on 19 Jun 2021 # +5 votes

A little update that the three "things still to do" are now all done. Most importantly, the last one - where if you change one task, your change propagates through the task tree. So if you know scheduling and was waiting for when to play with it, now is the time :)

D by duncan on 4 Jul 2021 #

@Moult @SigmaDimensions I guess you're aware of International Cost Management System, you are at least now https://icms-coalition.org/

T by tobenz on 4 Jul 2021 #

I was asked to switch over from Twitter ;). I wanted to join the 4D discussion (completely IFC based). As for now, the BlenderBIM implementation enforces a mandatory schedule or workplan that tasks belong to. The IFC schema, as I read it, suggests a different approach. There, a summary task has to relate to the IfcContext, and schedules or workplans are mandatory. That in my opinion is more flexible.

https://standards.buildingsmart.org/IFC/DEV/IFC4_3/RC1/HTML/schema/ifcprocessextension/lexical/ifctask.htm

The assignment of controls is not mandatory according to this.

So, wouldn't it be easier to just create tasks as a first level object and organize them using controls later on?

M by Moult on 4 Jul 2021, edited 4 Jul 2021 # +1 votes

This is an ambiguity in the documentation which we need to resolve.

The docs explicitly state that root level tasks must be declared to the project. Here is the evidence:

5.3.3.10 IfcWorkPlan

If an assigned IfcTask is a root-level task, such task must be declared on the IfcProject using the IfcRelDeclares relationship.

In addition, the docs also suggest that controls are optional. Here is the evidence:

5.3.3.6 IfcTask

Occurrences of IfcTask may be assigned to an IfcWorkControl

Therefore, at face value, you are absolutely correct that linking tasks to controls is optional.

However, the IFC docs need a bit of scrutiny, for example:

Why is this evidence for declaring root level tasks only mentioned on the IfcWorkPlan page, and not the IfcTask, IfcProcess, IfcRelAssignsToControl, IfcRelDeclares, or any other page?
IFC docs are written from the perspective of "finished" data, not WIP data where you first create tasks and then later organise them. So if having root tasks declared to a project is "finished" data, what does it actually mean for a user semantically? Does it have meaning?
Pre-IFC4, all tasks had to be declared to the project, but in IFC4, the declaration is indirect via a control. Is this evidence stale? Is it perhaps old documentation that needs to be removed?
Why are there no diagrams / figures showing this scenario?

For the moment, the IfcOpenShell API follows the docs as strictly as possible and does not prevent you from doing exactly what you're looking for - rooted tasks declared to projects with no controls, and later assigning controls. However, in the BlenderBIM Add-on UI, we have created a GUI that doesn't allow the user to do this - for the simple reason that we don't know what it means in practice, or how it benefits the user.

To resolve this, either:

Find a usecase for what you're mentioning that can be proposed to buildingSMART and documented more explicitly than the little hints that we are going off right now, and then we can re-jig the BlenderBIM Add-on UI to support it.
Discover that there is no strong usecase for what you're asking, and therefore remove all hints that suggest it exists.

From experience in implementing other portions of the spec where the spec seems to hint at flexibility, I've almost always discovered that this is not true - there is actually a "correct" way of doing it (as you'd expect from an ISO standard), just that the IFC wording needs to be improved to reduce ambiguity.

M by Moult on 4 Jul 2021 #

So basically, @tobenz can you come up with usecases and describe what it means for a rooted non-controlled task? When you've done so, I'll formalise it into a buildingSMART proposal and we can continue the discussion there to come to a conclusion.

D by drsola on 7 Jul 2022 #

Great work dear friends, I am new to this community. I want to thank all of you for the initiative and sacrifices to bring an open source BIM authoring tool to birth. I believe the BlenderBIM Add On will become a game changer on the global AEC sector. As a quantity surveyor , I want to know the progress made so far on the costing and scheduling module. What is the latest? How can we help?

D by drsola on 7 Jul 2022 #

@carlopav said:

maybe it's off-topic, but is there out there any simple software for traditional bill of quantities (calc apart)?

Yes. my team developed one ,qCloudCosting, that allows you to produce a BoQ based on any MoM of your choice. Infact we are thinking of developing its BIM successor. I will be willing to show the amazing volunteers behind BlenderBIM how it works. In order words we are willing to share our domain knowledge expertise with you dear self-sacrificing me in building the costing module of BlenderBIM

C by carlopav on 7 Jul 2022 #

@drsola thanks, i'll check it out.

D by duncan on 7 Jul 2022 #

@SigmaDimensions you've worked on quantities right?

D by drsola on 7 Jul 2022 #

@duncan said:

@SigmaDimensions you've worked on quantities right?

Yeah but using 2D drawings . My cost management expertise as a quantity surveyor could be of help

A by Ace on 2 May 2023, edited 2 May 2023 #

Not sure if there is a more applicable conversation,

But a quick question, does anyone know how to reorder task sequences displayed in the work schedule?

for example, task number and visual sequence doesn't match,

Not sure how to use this enable reorder button:

S by SigmaDimensions on 2 May 2023 #

hi @Ace,

There are two types of orderly things :

1- Enable Re-ordering : This change is kept in this ifc file.

2- Enable Sorting: This is purely visual

1- Re-ordering with the button only works for tasks that have sub_tasks, such that you can arrange the sub_tasks. You seem to only have summary tasks there- where is your tree?

2 - Enable Sorting will work in your Scenario:

Go to Enable Editing Work Schedule --> press "Schedule Columns" in the work_schedule settings --> Set the Column to "IfcTask" and "Identification" --> press on the Az button --> press the "+ add" button

You should have this:

Then, as a temp fix today, just press the "reverse_sort" button twice ( downward arrow) which will reload your task tree and sort it ( PS. yes this refreshing will be fixed)

A by Ace on 2 May 2023 #

Thanks @SigmaDimensions ! The visual sorting is really what I was after and that did the trick

"1- Re-ordering with the button only works for tasks that have sub_tasks, such that you can arrange the sub_tasks. You seem to only have summary tasks there- where is your tree?"

It's non-existant at the moment, Its definitely not correct at the moment, noted on the re-ordering