Indoor Geolocation: Coordinates of a Cake

(Click here to watch and listen to the video version of this blog entry)

Indoor geolocations are a special type of fun. Despite the premise being very similar to “normal” outdoor geolocations, the methods employed are significantly different. You cannot rely on image reverse search, landmark identification, or even the “I’m-desperate-enough-to-scan-this-entire-town-in-the-hopes-of-finding-the-damn place” technique. Indoor geolocations are all about the details. The more obscure the better. Anything can, and will, lead you the wrong path if you are not careful. But that is exactly what makes them so much fun.

The cake photo

A while ago I came across a photo of a cake whilst looking for an interesting challenge. I figured it was possible to pinpoint the exact location of where the cake was when the photo was taken. And by that I don’t mean the venue, I mean the exact coordinates of that cake. And indeed it was completely possible, therefore I decided to write an explanation of how I geolocated, and verified the coordinates of the cake seen below.

The photo contained many useful details which will be pointed out, and analysed in this text as I move along with the geolocation and verification process.

The Venue

The first step was finding the venue. The cake contained an inscription mentioning the “80th Anniversary” and “Birds – New Zealand”. A quick googling of all these keywords led me to an article titled “2019 New Zealand Bird Conference”. The last line of the text read “The Birds New Zealand conference will be held at the Brentwood Hotel and Conference Centre in Kilbirnie between 1st and 3rd June.“

Great start. I got the name of the venue. With that information I quickly found the hotel’s website and, as expected, they claim to provide venues for events. Eight conference rooms to be exact, just to make things slightly harder.

The Room

In order to figure out in which exact room the 2019 New Zealand Birds Conference was held I had to find a way to discern between their eight conference rooms. The Brentwood Hotel website had a “Conference” section with an “Options and Layouts” subcategory. Within that page I spotted various photos (1 – 4) showing a very familiar carpet. The first three images (1 – 3 in red) were of the same room, but from different angles. An additional one (4 in blue) was of a different conference room.

Photos of the conference rooms at Brentwood Hotel showing various venues with similar carpet pattern

The figure below shows a side by side comparison between the pattern of the carpet seen in the cake photo (left), and an identical pattern from one of the photos above (right).

Comparison between carpet pattern in cake photo and carpet from Brentwood Hotel conference room

By analysing all the photos within the hotel website I concluded that out of the eight conference rooms, only two had a similar carpet to the one seen in the cake photo; therefore I needed to find a way to tell these two conference rooms apart so I could eliminate the incorrect one. Within the website I found a pdf document with information about each of the conference rooms and their location within the hotel. A comparison between the photos above and the images on the document allowed me to identify the first three photos (1-3 red) as the Kauri room, whilst the other one with the same carpet (4 blue) was identified as the Tawa room.

Brentwood Hotel layout of conference rooms and locations - Kauri and Tawa rooms

Armed with the names of the rooms I went into the Hotel’s Facebook page and searched first for “Tawa” and then “Kauri”. With plenty of photos to analyse it did not take long to establish that the walls of the Tawa conference room were smooth, they did not have any panels. The Kauri room on the other hand had several panels, very similar to the ones seen on the background of the cake photo.

Below you can see the location of the wall panels within the Kauri room (bottom left), and the absence of a similar feature within the Tawa room (bottom right).

Presence of panel behind cake table on photo - Comparison between Kauri room which also has panels and Tawa room which has smooth walls

This information verified that the photo was taken inside the Kauri conference room. This was already expected based on the number of plates seen in the cake photo. I counted around 17-19 plates per stack, and with four stacks visible it is likely the event was expecting over 68 people. The Tawa room does not seem to be able to cater for that many attendees.

It is therefore clear that the cake was inside the Kauri room. However, according to the Brentwood Hotel, the Kauri room is divided into four different sections which can be opened up as needed. I was looking for precision so I needed to figure out in which exact section of the Kauri room the cake was located at the time of the conference. The hotel’s website provided a detailed layout of the rooms and where each section was divided. Unfortunately the image of the layout was rotated to the exact opposite angle of the photo showing the entire length of the Kauri room to make things slightly confusing. Below is my attempt at explaining which part is K1 (Kauri room 1), K2 (Kauri room 2), K3 (Kauri room 3), and K4 (Kauri room 4).

Explanation of location of Kauri room sections using photo and layout image from Brentwood Hotel

Knowing that the cake was placed near the panels, it is possible to infer that we are looking for a location within Kauri room 1. But I wanted to be even more accurate.

You may have noticed in the model seen above that there are five panels on Kauri room 1. Unfortunately that information is incorrect and I can prove it.

The Brentwood Hotel shared a video on their Facebook page showing a timelapse of the Kauri room being opened up to connect all four sections. It is possible to count six panels in the footage, as seen in the figure below on the left. Additionally, I found a photo from a different event that took place in the Kauri room in 2022 in which you can count the panels in the background, as seen in the figure below on the right. I then matched the details where the carpet met the panels (highlighted on panel 3) to prove there were six, not five panels in total.

Verification of the presence of six panels on walls of Kauri room by comparing screenshot from Facebook video and photo from different conference

The Panel

At this point I established the cake photo was in front of one of the panels in Kauri room 1 but I still wanted to figure out the exact location. And for that I, once again, resorted to looking at details.

The cake photo had something interesting on the top corner. I could see a bit of a shadow being cast.

Small shadow in corner of cake photo pointing out to presence of a wall and skirting board

This told me that I was looking at the last panel before the wall. The bottom of the shadow, where the neon green arrow is pointing in the image above, was very likely the skirting board. In order to prove my theory I checked a couple photos from the Brentwood Hotel photo gallery to establish that there was a wall which could cast a shadow next to the last panel (left), and that the wall within the Kauri room 1 had a skirting board (right).

Further proof of presence of wall next to last panel in Kauri room and skirting board along walls

It was then possible to infer that the last panel seen in the cake photo was the panel closest to the wall, also referred earlier as panel number 6. This would put the cake between panel panel 3 and 4, as seen below.

Counting panels behind cake table - Visible panels from 3 to 6

I verified this information by comparing the carpet in the cake photo (middle) and the video on the Brentwood Hotel’s Facebook page showing staff members opening up the Kauri room (right).

By analysing the area near panel 4 and 5 in both figures it was possible to verify how the details match.

Highlighting of details on carpet near panels 4 and 5 of Kauri room

Interestingly enough, when analysing the table layout on the photo I found on Facebook of a conference in the Kauri room in 2022 (right), I noticed some similarities. The table with the stack of plates was at the same angle and in the same location as the cake photo from 2019 (left). Possibly one of the go-to catering layouts for the hotel.

Comparison between table location and panel numbers on cake photo and of a different image from a 2022 conference with table in the same angle

The Coordinates

After confirming and verifying the location of the table with the cake I needed to get the coordinates. To start, I mapped the location of the table within the room as seen below (white), and then noted that it was lined up almost exactly in the middle of the two narrow windows at the top of the panels.

Location of cake table within Kauri room 1 and line showing position according to top windows

With that information I could go back to the layout of the hotel which I found on the website and locate where the table with the cake would have been placed (left). Knowing the angle and position of the pool in relation to the specific panels within Kauri room 1, I could then also pinpoint the location of the cake on satellite image (right).

Table position on Brentwood Layout showing location within Kauri room 1 and same location as seen in satellite imagery

The coordinates of the cake for the 80th Anniversary of Birds New Zealand Conference in 2019 were: -41.316023, 174.797297.

Conclusion

Geolocations are addictive and fun but indoor geolocations are on a whole new level. The potential for this type of intelligence is impressive (and a bit scary). If you are ever bored of “normal” geolocations I invite you to start geolocating random objects indoors. They will definitely keep you busy.

Thank you for reading.

~Sofia.