Overlay Settings

[MelanieNeedle]

Hello:

I am looking for a description of the effect the advanced overlay settings have on the total allowed units metric reported in the building regulation panel.  The ArcGIS Urban documentation  doesn't seem to describe the options fully and the effect the overlays have on the metrics. The options are default (replace zoning), maximum, minimum, and subtract. I also cant seem to remember where the user sets the "development behavoir" of the overlays. In my case, I am using natural resources as overlays to limit density potential. 

Thanks,

Melanie

[DominikAllemann]

Hi @MelanieNeedle ,

Happy New Year, and thanks for your question. 

Advanced overlay settings

The advanced overlay settings let you configure how the zoning parameters configured on an overlay boundary interact with zoning parameters of the underlying zoning boundaries. 

By default, a zoning parameter configured on an overlay boundary replaces the zoning parameter of the underlying zone. 

The remaining 4 options have the following effect:

• Maximum: the zoning parameter on the underlying zone is only replaced if the corresponding zoning parameter on the overlay boundary is higher than the one on the zone.
• Minimum: the zoning parameter on the underlying zone is only replaced if the corresponding zoning parameter on the overlay boundary is lower than the one on the zone.
• Add: the zoning parameter value on the underlying zone is added to the corresponding value on the overlay boundary. 
• Subtract: The zoning parameter value on the overlay boundary is subtracted from the corresponding value on the underlying zone.

Number of dwelling units as reported in the building regulation panel

The number of dwelling units as reported in the building regulation panel is driven by two factors:

• The parcel area
• The applicable "Dwelling units density" value for the given parcel. This value can either be configured on the zoning, overlay or parcel level. See Zoning regulation management in our docs to learn more about where you can configure zoning regulations.

Generally, a zoning parameter configured on an overlay replaces the corresponding value of the underlying zone. Any zoning parameter configured on the parcel level, replaces the corresponding value of the underlying zone and overlay.

Effect of overlays on metrics

Would you mind providing an example of what you mean by "what effect the overlays have on metrics"?

In case of further questions, please don't hesitate to reach out.

Thanks,

Dominik

[MelanieNeedle]

Thanks for the detailed description. 

 Would you mind providing an example of what you mean by "what effect the overlays have on metrics"?

Here is the example. The overlay parameter for the green hatched area is set to 0% coverage and replace zoning is chosen in the advanced overlay settings, but a total allowed units of 15 dwelling units is still reported. Also, the overlay doesn't cover the whole parcel. The parcel is about 76 acres, and the zoning density is .2 du/acre, so it seems like the overlay is not taken into account in this example.

Thanks!

[DominikAllemann]

Hi @MelanieNeedle ,

Thanks for sharing the screenshot. 

How Urban determines the zoning parameters applicable to a parcel

Urban uses the parcel centroid to determine the relevant zoning parameters from zones and overlays for a given parcel. To calculate the parcel centroid, Urban applies an approach where the centroid is always inside the parcel geometry - e.g., for concave parcels.

In the example you shared, it looks as if the parcel's centroid is just outside the green-hatched overlay area. Therefore, the overlay coverage value of 0% is not reflected in the building regulation side panel.

"Allowed" zoning parameters in building regulation side panel

The "Allowed" column in the building regulation side panel reports what's maximally allowed for each zoning parameter individually. The values reported there do not change depending on other parameters' values. 
In your case, a 0% coverage won't impact the reported number of dwelling units in the "Allowed" column of the building regulation side panel. 

The interdependency among the different zoning parameters comes into play when you develop a parcel by applying a building type. If your parcel doesn't allow any coverage (0%), you'll see that no dwelling units will be built when applying a dwelling units building type on that parcel. When a parcel is developed, you'll see a second column called "Built" in the building regulation side panel. 

To learn more about working with dwelling units in ArcGIS Urban, I can highly recommend this blog post.

Thanks,
Dominik

[MelanieNeedle]

Thanks Dominik! I am still looking for a solution to account for natural resource constraints that limit development potential of Allowed units because I am not taking the next step of applying building types. Would the parcel suitability model functionality work for what I am trying to do? Do you have a link to a webinar or tutorial on the parcel suitability model?

[DominikAllemann]

Hi @MelanieNeedle ,

Thanks for your question. 

The suitability tool allows you to assess whether a parcel is suitable for development based on various criteria, ranging from parcel and zoning properties to almost any other criteria from an external layer. 

It definitely sounds like it's worth it for you to explore the suitability tool's capabilities, even though I don't know the details of your challenge at hand.

The following resources might be of interest to you:

• High-level blog post about the suitability tool
• What's New Webinar from Summer 2021 where the tool was introduced - fast forward to 18:37.
• Documentation

In case of questions, please reach out.

Dominik

[MelanieNeedle]

@DominikAllemann Thanks for the resources. The suitability tool is not going to give me the outcome I am looking for. Essentially, I am looking for a solution (hopefully) within ArcGISUrban that reduces the total allowed units on a parcel based on undevelopable area. 

[DominikAllemann]

@MelanieNeedle , thanks for your feedback. 
I'm sorry to hear that the suitability tool cannot contribute to the solution of the task you are trying to solve. If you have more questions about Urban's tools and features, please don't hesitate to reach out. 

[MelanieNeedle]

@DominikAllemann Are there plans for enhancement to ArcGIS Urban so that it computes parcel geometry based on an external layer's area which identifies undevelopable areas and then reports the total allowed units based on the developable area? 

I would love this functionality of a basic build out analysis within ArcGIS Urban as its an essential function of most planning offices. 

[DominikAllemann]

@MelanieNeedle support for better distinguishing undevelopable vs. developable areas might be added to Urban in the longer term.

For now, I'd recommend two things:
1) Use the existing tools provided by Esri's product portfolio in general and ArcGIS Urban in particular to build a workflow that helps you solve the task.
Please let me know if you and your organization would need support with this. We could connect you with a subject matter expert from our Consulting Services team.

2) Feel free to submit an ArcGIS Urban product idea with as many details as possible. This helps us better understand your particular use case, and other users can share their thoughts and upvote your idea if they face similar tasks that need to be accomplished.