NoMethodError in PicturesController#new

def find_portfolio
    @portfolio = @user.portfolios.find(params[:portfolio_id])
end

class PicturesController < ApplicationController
  before_filter :authenticate_user!, only: [:new, :create, :edit, :update, :destroy]
  before_filter :find_user
  before_filter :find_portfolio

  # GET /pictures
  # GET /pictures.json
  def index
    @pictures = @portfolio.pictures.all
  end

  # GET /pictures/1
  # GET /pictures/1.json
  def show
  end

  # GET /pictures/new
  def new
    @picture = @portfolio.pictures.new
  end

  # GET /pictures/1/edit
  def edit
  end

  # POST /pictures
  # POST /pictures.json
  def create
    @picture = @portfolio.pictures.new(picture_params)

    respond_to do |format|
      if @picture.save
        format.html { redirect_to @picture, notice: 'Picture was successfully created.' }
        format.json { render action: 'show', status: :created, location: @picture }
      else
        format.html { render action: 'new' }
        format.json { render json: @picture.errors, status: :unprocessable_entity }
      end
    end
  end

  # PATCH/PUT /pictures/1
  # PATCH/PUT /pictures/1.json
  def update
    respond_to do |format|
      if @picture.update(picture_params)
        format.html { redirect_to @picture, notice: 'Picture was successfully updated.' }
        format.json { head :no_content }
      else
        format.html { render action: 'edit' }
        format.json { render json: @picture.errors, status: :unprocessable_entity }
      end
    end
  end

  # DELETE /pictures/1
  # DELETE /pictures/1.json
  def destroy
    @picture.destroy
    respond_to do |format|
      format.html { redirect_to pictures_url }
      format.json { head :no_content }
    end
  end

  def url_options
    { username: params[:username] }.merge(super)
  end

  private   
    def find_user
      @user = User.find_by_username(params[:username])
    end

    def find_portfolio
        @portfolio = @user.portfolios.find(params[:portfolio_id])
    end

    def find_picture
      @picture = @porfolio.pictures.find(params[:id])
    end
    def picture_params
      params.require(:picture).permit(:caption, :description, :portfolio_id, :user_id)
    end
end

<%= simple_form_for(@portfolio, @picture), html: { class: 'form-horizontal'} do |f| %>
  <% if @picture.errors.any? %>
    <div id="error_explanation">
      <h2><%= pluralize(@picture.errors.count, "error") %> prohibited this picture from being saved:</h2>

      <ul>
      <% @picture.errors.full_messages.each do |msg| %>
        <li><%= msg %></li>
      <% end %>
      </ul>
    </div>
  <% end %>


  <div class="form-inputs">
    <%= f.input :caption %>
    <%= f.input :description %>
  </div>
  <div class="form-actions">
    <%= f.button :submit %>
  </div>
<% end %>