diff --git a/CHANGELOG.md b/CHANGELOG.md
index ffae9d70..80eb84e5 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,13 @@
 ## Changes since last CRAN release
-* `8a7d56e6 (HEAD -> master)` [_`dipterix`_]: Fixed a singular matrix bug when the electrode prototype `up` vector is zero or is parallel with the model direction
-* `dd16370a (origin/master, origin/HEAD)` [_`dipterix`_]: Allowed the surface mapped electrodes to be snapped to the surface if the surface world matrix is not identity; Force the inflated brain to have offset positions
+* `72e4487f (HEAD -> master)` [_`dipterix`_]: Added internal test code for depth mapping
+* `d0f93db6` [_`dipterix`_]: Surface mapping has been implemented for depth electrodes, with dynamic offset threshold
+* `8f9ab813` [_`dipterix`_]: `surface_offset` has been added to electrode field
+* `b9ef710d` [_`dipterix`_]: `cvs_avg35_inMNI152` has the correct `talXFM` (scanner to `MNI305`) now
+* `bb328b96` [_`dipterix`_]: Added `load_mesh` to surface object so users can load surface mesh for computation in `R`; Added internal `calculate_distances` to compute the distances from a point to its projection to a list of mesh
+* `02165822` [_`dipterix`_]: `DistanceShifted` in electrode table is taken into account and will be passed to electrode instances
+* `f703c24b` [_`dipterix`_]: Inflated surfaces have offset by default
+* `988fd65e (origin/master, origin/HEAD)` [_`dipterix`_]: Fixed a singular matrix bug when the electrode prototype `up` vector is zero or is parallel with the model direction
+* `dd16370a` [_`dipterix`_]: Allowed the surface mapped electrodes to be snapped to the surface if the surface world matrix is not identity; Force the inflated brain to have offset positions
 * `18df6e14` [_`dipterix`_]: Bump `dev` version
 * `074adfb1` [_`dipterix`_]: Added `DBS` electrode prototype `BSC-DB-2202`
 * `00ba2111` [_`dipterix`_]: Prototype `set_transform_from_points` now tries to set rotation from transform `Euler` angle when the prototype guided marker is 1-ranked (electrode strip, `DBS` electrodes)
diff --git a/DESCRIPTION b/DESCRIPTION
index a0f8bc55..f4f59190 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -1,7 +1,7 @@
 Package: threeBrain
 Type: Package
 Title: Your Advanced 3D Brain Visualization
-Version: 1.1.1.9002
+Version: 1.1.1.9003
 Authors@R: c(
     person("Zhengjia", "Wang", email = "dipterix.wang@gmail.com", role = c("aut", "cre", "cph")),
     person("John", "Magnotti", email = "John.Magnotti@Pennmedicine.upenn.edu", role = c("ctb", "res")),
diff --git a/adhoc/surface_mapping.R b/adhoc/surface_mapping.R
new file mode 100644
index 00000000..14464b13
--- /dev/null
+++ b/adhoc/surface_mapping.R
@@ -0,0 +1,288 @@
+raveio::raveio_setopt("raw_data_dir", "/Volumes/BeauchampServe/rave_data/raw")
+raveio::raveio_setopt("data_dir", "/Volumes/BeauchampServe/rave_data/ent_data/")
+
+project_name <- "mTurkWords"
+subject_code <- "YEZ"
+template_name <- "cvs_avg35_inMNI152"
+
+electrodes <- "36-39,46-49,93-99,111-113,139-140,142,145-152,205-208"
+
+max_distance <- 3
+
+# ---- Load data ---------------------------------------------------------------
+subject <- raveio::RAVESubject$new(project_name = project_name,
+                                   subject_code = subject_code)
+brain <- raveio::rave_brain(subject)
+
+electrode_coords <- brain$electrodes$raw_table[
+  brain$electrodes$raw_table$Electrode %in% dipsaus::parse_svec(electrodes),
+]
+
+# Load surfaces
+# Run with Coord_xyz
+obj_pial <- brain$add_surface("pial")
+obj_white <- brain$add_surface("smoothwm")
+if(is.null(obj_white)) {
+  obj_white <- brain$add_surface("white")
+}
+obj_sphere_reg <- brain$add_surface("sphere.reg")
+obj_sphere <- brain$add_surface("sphere")
+
+# Load surfaces into memory
+pial <- list(
+  left = obj_pial$load_mesh("left"),
+  right = obj_pial$load_mesh("right")
+)
+white <- list(
+  left = obj_white$load_mesh("left"),
+  right = obj_white$load_mesh("right")
+)
+sphere_reg <- list(
+  left = obj_sphere_reg$load_mesh("left"),
+  right = obj_sphere_reg$load_mesh("right")
+)
+sphere <- list(
+  left = obj_sphere$load_mesh("left"),
+  right = obj_sphere$load_mesh("right")
+)
+
+sulc <- list(
+  left = freesurferformats::read.fs.curv(file.path(brain$base_path, "surf", "lh.sulc")),
+  right = freesurferformats::read.fs.curv(file.path(brain$base_path, "surf", "rh.sulc"))
+)
+curv <- list(
+  left = freesurferformats::read.fs.curv(file.path(brain$base_path, "surf", "lh.curv")),
+  right = freesurferformats::read.fs.curv(file.path(brain$base_path, "surf", "lh.curv"))
+)
+aparc_2009 <- list(
+  left = freesurferformats::read.fs.annot("/Volumes/BeauchampServe/rave_data/raw/YEZ/rave-imaging/fs/label/lh.aparc.a2009s.annot"),
+  right = freesurferformats::read.fs.annot("/Volumes/BeauchampServe/rave_data/raw/YEZ/rave-imaging/fs/label/rh.aparc.a2009s.annot")
+)
+
+stats <- structure(
+  names = names(aparc_2009),
+  lapply(names(aparc_2009), function(hemi) {
+    aparc <- aparc_2009[[hemi]]
+    ROI_table <- aparc$colortable_df#[aparc$colortable_df$struct_name %in% c('S_temporal_sup', aparc$colortable_df$struct_name[grepl("temp_sup", aparc$colortable_df$struct_name)]),]
+
+    sel <- aparc$label_codes %in% ROI_table$code
+    sts_nodes <- aparc$vertices[sel] + 1
+    sts_color <- aparc$hex_colors_rgb[sel]
+
+    # # Find lowest sulc
+    # sv <- curv[[hemi]][sts_nodes]
+    # pos <- white[[hemi]]$vertices[sts_nodes, , drop = FALSE]
+    #
+    # # A-P for each 1mm, find valley
+    # rg <- range(pos[, 2])
+    # rg <- c(floor(rg[[1]]), ceiling(rg[[2]]))
+    # by <- 0.5
+    # anteriors <- seq(rg[[1]], rg[[2]] - by, by = by)
+    # pos_a <- pos[, 2]
+    # valley_subidx <- sapply(anteriors, function(a) {
+    #   sel <- which(pos_a > a & pos_a < (a+by))
+    #   if(!length(sel)) { return(NA) }
+    #   idx <- which.max(sv[sel])
+    #   sel[idx]
+    # })
+    # valley_subidx <- valley_subidx[!is.na(valley_subidx)]
+    #
+    # valley_idx <- sts_nodes[valley_subidx]
+
+    list(
+      nodes = sts_nodes,
+      # valley = valley_idx,
+      color = sts_color
+    )
+  })
+)
+
+
+
+# ---- Fix the hemisphere ------------------------------------------------------
+tkr_ras <- as.matrix(electrode_coords[, c("Coord_x", "Coord_y", "Coord_z")])
+
+dist_to_pial <- threeBrain:::calculate_distances(positions = tkr_ras, mesh_list = list(
+  left = list(vertices = pial$left$vertices[stats$left$nodes,,drop = FALSE]),
+  right = list(vertices = pial$right$vertices[stats$right$nodes,,drop = FALSE])
+))
+dist_to_pial$left$index <- stats$left$nodes[dist_to_pial$left$index]
+dist_to_pial$right$index <- stats$right$nodes[dist_to_pial$right$index]
+dist_to_white <- threeBrain:::calculate_distances(positions = tkr_ras, mesh_list = list(
+  left = list(vertices = white$left$vertices[stats$left$nodes,,drop = FALSE]),
+  right = list(vertices = white$right$vertices[stats$right$nodes,,drop = FALSE])
+))
+dist_to_white$left$index <- stats$left$nodes[dist_to_white$left$index]
+dist_to_white$right$index <- stats$right$nodes[dist_to_white$right$index]
+
+# Using white-matter for distance calculation
+distances <- dist_to_white
+hemisphere <- ifelse(distances$right$distance < distances$left$distance, "right", "left")
+sel <- tolower(electrode_coords$Hemisphere) %in% c("right", "left")
+hemisphere[sel] <- electrode_coords$Hemisphere[sel]
+electrode_coords$Hemisphere <- hemisphere
+
+calc_dijkstras <- function(hemi, obj, max_dist = 50) {
+  is_hemi <- !is.na(hemisphere) & hemisphere == hemi
+  node_hemi <- distances[[hemi]]$index[is_hemi]
+  vert_hemi <- obj[[hemi]]$vertices
+  face_hemi <- obj[[hemi]]$faces
+
+  prefix <- electrode_coords$LabelPrefix[is_hemi]
+  dijkstras_paths <- lapply(seq_len(length(node_hemi) - 1), function(ii) {
+    idx <- which(prefix == prefix[[ii]])
+    idx <- idx[idx > ii]
+    if(!length(idx)) { return(NULL) }
+    dijkstras_hemi <- ravetools::dijkstras_surface_distance(
+      positions = vert_hemi,
+      faces = face_hemi,
+      start_node = node_hemi[[ii]],
+      max_search_distance = max_dist,
+      face_index_start = 1
+    )
+
+    dists <- sapply(idx, function(jj) {
+      path <- ravetools::surface_path(dijkstras_hemi, target_node = node_hemi[[ jj ]])
+      dist <- path$distance[[nrow(path)]]
+      if(is.na(dist)) { dist <- Inf }
+      dist
+    })
+
+    jj <- idx[which.min(dists)][[1]]
+    path <- ravetools::surface_path(dijkstras_hemi, target_node = node_hemi[[ jj ]])
+
+    path
+  })
+
+  dijkstras_paths
+
+}
+
+dijkstras <- list(
+  left = calc_dijkstras('left', white),
+  right = calc_dijkstras('right', white)
+)
+
+# visualize
+snapshot <- function(hemi, obj, plot_orig = TRUE, plot_paths = TRUE, cex = 1) {
+  is_hemi <- !is.na(hemisphere) & hemisphere == hemi
+  tkr_hemi <- tkr_ras[is_hemi,, drop = FALSE]
+  node_hemi <- distances[[hemi]]$index[is_hemi]
+
+  label_predix <- factor(electrode_coords$LabelPrefix[is_hemi], levels = sort(unique(electrode_coords$LabelPrefix)))
+
+  # white_proj_hemi <- distances[[hemi]]$position[is_hemi, , drop = FALSE]
+
+  vert_hemi <- obj[[hemi]]$vertices
+  # face_hemi <- obj[[hemi]]$faces
+  # valley_node_hemi <- stats[[hemi]]$valley
+  sulc_node_hemi <- stats[[hemi]]$nodes
+  # curv_hemi <- curv[[hemi]][sulc_node_hemi]
+
+  proj_hemi <- vert_hemi[node_hemi,, drop = FALSE]
+
+  range_hemi <- apply(vert_hemi[sulc_node_hemi,,drop = FALSE], 2, range)
+  range_hemi[1, ] <- floor(range_hemi[1, ])
+  range_hemi[2, ] <- ceiling(range_hemi[2, ])
+
+  # prefix <- electrode_coords$LabelPrefix[is_hemi]
+  dijkstras_paths <- dijkstras[[hemi]]
+
+  col <- rep(dipsaus::col2hexStr("gray90", alpha = 0.2), nrow(vert_hemi))
+  col[sulc_node_hemi] <- dipsaus::col2hexStr(stats[[hemi]]$color, alpha = 0.2)
+
+  # if(hemi == "left") {
+  #   valley_sel <- sulc_node_hemi[curv_hemi > 0 & curv_hemi < 0.05]
+  # } else {
+  #   valley_sel <- sulc_node_hemi[curv_hemi < 0 & curv_hemi > -0.05]
+  # }
+  #
+  # col[valley_sel] <- "black"
+  # col[valley_node_hemi] <- "black"
+
+
+  elec_cols <- threeBrain:::DEFAULT_COLOR_DISCRETE[as.integer(label_predix)]
+
+  # Visualize projection
+  # par(mfrow = c(2, 2), mar = c(0, 0, 0, 0))
+  # Coronal
+  lapply(list(
+    c(1, 3), c(2, 3), c(1, 2)
+  ), function(o) {
+
+    # plot(vert_hemi[, o], pch = ".", asp = 1, axes = FALSE, col = col)
+    # points(tkr_hemi[, o], pch = 1, col = elec_cols, cex = cex)
+    # points(white_proj_hemi[, o], pch = 20, col = elec_cols, cex = cex)
+
+    plot(vert_hemi[, o], pch = ".", asp = 1, axes = FALSE, col = col,
+         xlim = range_hemi[, o[[1]]], ylim = range_hemi[, o[[2]]])
+    if(plot_orig) {
+      points(tkr_hemi[, o], pch = 1, col = elec_cols, cex = cex)
+      arrows(x0 = tkr_hemi[, o[[1]]], x1 = proj_hemi[, o[[1]]], y0 = tkr_hemi[, o[[2]]], y1 = proj_hemi[, o[[2]]], col = elec_cols, length = 0.05)
+    }
+    points(proj_hemi[, o], pch = 20, col = elec_cols, cex = cex)
+
+    # lapply(seq_along(node_hemi), function(ii) {
+    #   path <- ravetools::surface_path(dijkstras_hemi, target_node = node_hemi[[ ii ]])
+    #   if(length(path) > 0 && nrow(path) > 1) {
+    #     path_coords <- vert_hemi[path$path, o, drop = FALSE]
+    #     nr <- nrow(path_coords)
+    #     x0 <- path_coords[1:(nr-1),1]
+    #     y0 <- path_coords[1:(nr-1),2]
+    #     x1 <- path_coords[2:nr,1]
+    #     y1 <- path_coords[2:nr,2]
+    #     segments(x0, y0, x1, y1, col = elec_cols[[ii]], lwd = 1)
+    #   }
+    # })
+    if( plot_paths ) {
+      lapply(dijkstras_paths, function(path) {
+        if(length(path) > 0 && nrow(path) > 1) {
+          path_coords <- vert_hemi[path$path, o, drop = FALSE]
+          nr <- nrow(path_coords)
+          x0 <- path_coords[1:(nr-1),1]
+          y0 <- path_coords[1:(nr-1),2]
+          x1 <- path_coords[2:nr,1]
+          y1 <- path_coords[2:nr,2]
+          segments(x0, y0, x1, y1, col = "black", lwd = 1)
+        }
+      })
+    }
+
+  })
+  invisible(dijkstras_paths)
+}
+par(mfrow = c(3, 3), mar = c(0, 0, 0, 0))
+cex = 2
+# snapshot('left', pial, plot_orig = TRUE, plot_paths = FALSE, cex = cex)
+# snapshot('left', pial, plot_orig = FALSE, plot_paths = TRUE, cex = cex)
+# snapshot('left', sphere, plot_orig = FALSE, cex = cex)
+
+snapshot('right', pial, plot_orig = TRUE, plot_paths = FALSE, cex = cex)
+snapshot('right', pial, plot_orig = FALSE, plot_paths = TRUE, cex = cex)
+snapshot('right', sphere, plot_orig = FALSE, cex = cex)
+
+
+
+# ---- Map to template surfaces ------------------------------------------------
+# electrode_coords$SurfaceElectrode <- TRUE
+electrode_coords$DistanceShifted <- 0
+sel <- !is.na(hemisphere) & hemisphere == "left"
+electrode_coords[sel, c("Sphere_x", "Sphere_y", "Sphere_z")] <- sphere_reg$left$vertices[ distances$left$index[sel], , drop = FALSE ]
+electrode_coords[sel, "DistanceShifted"] <- distances$left$distance[sel]
+sel <- !is.na(hemisphere) & hemisphere == "right"
+electrode_coords[sel, c("Sphere_x", "Sphere_y", "Sphere_z")] <- sphere_reg$right$vertices[ distances$right$index[sel], , drop = FALSE ]
+electrode_coords[sel, "DistanceShifted"] <- distances$right$distance[sel]
+
+brain <- raveio::rave_brain(subject)
+brain$set_electrodes(electrode_coords, priority = "sphere")
+brain$set_electrode_values()
+brain$add_surface("sphere.reg")
+brain$add_surface("inflated")
+brain$add_surface("smoothwm")
+
+template <- threeBrain::merge_brain(brain, template_subject = template_name)
+template$template_object$add_surface("inflated")
+template$template_object$add_surface("sphere.reg")
+template$template_object$add_surface("smoothwm")
+template$plot(additional_subjects = brain$subject_code)
+merge_brain