View Analysis_view distance and direction to a particular building facade

Nate · March 22, 2022, 8:01pm

Hi, community.
The new Ladybug tool 1.4.0 is awsome. I have been running tests to study the visibility between building facades and street points with LB&HB. With the component of “VisibilityPercent”, it’s able to find out how many points are visible to the building facades. But when a maximum view distance is given, how could I find out how many points are not visible within the given distance.

ViewAnalysis_Distance_Directions.gh (25.9 KB)
A few more questions can be found in the upload image or .gh file. Any idea about those things?
Best

chris · March 29, 2022, 1:56am

This is a good question but it’s probably going to need an extra calculation. Essentially, you’ll have to first figure out the number of _view_points that are within a given distance of a particular grid point. Once you have that, it’s pretty easy. You’ll just have to edit this line of code inside the component:

github.com

ladybug-tools/ladybug-grasshopper/blob/master/ladybug_grasshopper/src/LB Visibility Percent.py#L147

    
      
          int_mtx = objectify_output('Visibility Intersection Matrix', int_matrix)
          vec_count = len(_view_points)
          if pt_weights_:  # weight intersections by the input point weights
              tot_wght = sum(pt_weights_) / vec_count
              adj_weights = [wght / tot_wght for wght in pt_weights_]
              results = []
              for int_vals in int_matrix:
                  w_res = [ival * wght for ival, wght in zip(int_vals, adj_weights)]
                  results.append(sum(w_res) * 100 / vec_count)
          else:  # no need to wieght results
              results = [sum(int_list) * 100 / vec_count for int_list in int_matrix]
          
          
# create the mesh and legend outputs
          graphic = GraphicContainer(results, study_mesh.min, study_mesh.max, legend_par_)
          graphic.legend_parameters.title = '%'
          if legend_par_ is None or legend_par_.are_colors_default:
              graphic.legend_parameters.colors = Colorset.view_study()
          title = text_objects(
              'Visibility Percent', graphic.lower_title_location,
              graphic.legend_parameters.text_height * 1.5,
              graphic.legend_parameters.font)

Essentially, you’ll want to divide by the number of points within the distance rather than the vec_count (aka. the total number of points). You’ll also probably need something to catch the case that no points are within the max_dist_ since you’ll otherwise get a ZeroDivisionError.

If enough people here find this useful, maybe we can add something for this natively in the official component.

AbrahamYezioro · March 29, 2022, 3:01am

Hi @chris,
i can find this useful. Handy.
-A.

Nate · March 29, 2022, 3:12am

Hi, Chris.
Thanks, that’s impressive. I am new to Grasshopper/Ladybug and still trying to figure out how those components work, what they can/cannot do. Also, I am not familiar with the programming/code thing, but I definitely have to try it out. The visibility analysis component is powerful and I believe it could be much better. There is a lot more that can be improved. Once I got something new, I’ll have you updated.
Thanks again.
Best

chris · March 29, 2022, 1:47pm

Ok I opened an issue for this on out GitHub:

github.com/ladybug-tools/ladybug-grasshopper

Enable Visibility Analysis component to report the percent of points seen within max_dist_

opened 01:45PM - 29 Mar 22 UTC

chriswmackey

enhancement wish

This shouldn't be terribly difficult to add. Essentially, you'll have to firs…t figure out the number of `_view_points` that are within a given distance of a particular grid point. Once you have that, it's pretty easy. You'll just have to edit this line of code inside the component: https://github.com/ladybug-tools/ladybug-grasshopper/blob/master/ladybug_grasshopper/src/LB%20Visibility%20Percent.py#L147 Essentially, you'll want to divide by the number of points within the distance rather than the `vec_count` (aka. the total number of points). You'll also probably need something to catch the case that no points are within the `max_dist_` since you'll otherwise get a ZeroDivisionError. More information is here: https://discourse.ladybug.tools/t/view-analysis-view-distance-and-direction-to-a-particular-building-facade/17778/2

Because this is a good issue for anyone interested in contributing to tackle and it isn’t pressing, I’d like to leave it there for a while to see if anyone else would like to implement it.

If it’s still not implemented after some time, I’ll add it.

Nate · May 20, 2022, 6:59am

@chris The gap is not filled yet. It’ll be great help for me if you could kindly fix this.
Thanks.