Return state based on calculated position on temperature-humidity chart

I’m trying to replace my ERV controller with an ESPHome device and some HA automations (probably Node-Red or possibly just on the ESP). My ERV controller has this chart that shows which mode is active based on the internal and external temperature and humidity. My goal is to recreate the logic of this chart in HA and ultimately produce a sensor with a state that matches the ERV mode shown on the chart for given temperature and humidity values. From there, I’m planning on recreating the controller’s behavior, but right now, I’m just trying to get the mode as a sensor state.

I found one thread where someone was doing something very similar for plant vapor pressure deficit (VPD) calculations but the one response there was only with respect to displaying results on a chart card, not returning a state based on the calculations: Dynamically position icon on VPD chart.

Given that the lines on the chart don’t seem to be derived from a set of formulas, I’m not sure how to accomplish this goal. It would be extremely time-consuming to generate temperature-humidity pairs and build out a sensor based on those, but that’s the closest thing I’ve thought of so far. My hope is that there is some chart positional reading software out there which may solve this.

Does anyone have any advice on how to approach this problem?


You could make the raster smaller and make a lookup table, don’t know how much memory that would consume though.